I like side-quests that flow well, and give you more insight into the game world. The huge problem I had with Skyrim, for example, is how dead the world really felt. Everything was really far away from where you picked up the quest, but the journey never really felt worthwhile. The caves you had to dive into didn't have any real significance, the forts and ruins were bland, and everything in general just felt sort of empty. For a province that is supposedly dealing with a huge civil war, the world certainly didn't reflect that too well. Sure, you'd see a group of Stormcloaks fighting a few Imperials, but for the most part, everything was so open that it just never felt important. The only real information you'd get on Skyrim was through books, which is fantastic and all, but even Morrowind, released back in 2002, had NPCs that you could ask questions of that weren't just "where can I buy more swords?". The whole "see that mountain? You can go there!" marketing didn't make a damn bit of difference, because once you got to that mountain, you discovered it was just a part of the backdrop and meant absolutely nothing. Big freaking deal. You walked up a mountain with a demonic anti-gravity horse. Yay you. Go do something useful.
Quests that make the player feel like he or she is making a difference mean so much. Look at Ultima VII:The Black Gate. Widely regarded as one of the best RPGs in existence and the grandfather of many the games we play nowadays, the side quests were enjoyable, engaging, and really brought Britannia to life. You actually learned to love or hate certain NPCs, feel sorry for them, etc. While there were plenty of issues with the main quest(what a huge nightmare that was), the world was alive. Breathing. Filled with people with a story to tell, an agenda, personality. Few games have come out like it since.
There's a few flavors of side-quest that you really have to pick from, and if they stand on their own, they're god awful if you really think about it. Half of them your character shouldn't have a reason to be involved with in the first place. Why a guy with a problem would wait around for a specific group of weirdly dressed, murder-happy, loot-hungry strangers before asking for help with his problem is beyond me. Is everyone around really that useless? Is he just lazy? Or oddly trusting of complete strangers he's never met? The rewards usually don't outweigh even performing these mundane tasks to begin with. Not just item rewards, but the experience of going and doing a side-quest often feels like just another motion, a mechanical reflex of being a gamer, in the hope that you'll get something shiny for your efforts.
Most side-quests seem to be broken down as such:
Go Get Me a Thing-There's a book under that bridge over there. I really need it. I'd pick it up myself, since the bridge in question is about 20 yards away, but you see, I'm really enjoying this beautiful day. Please? I'll give you my lunch. Don't ask what I'm going to eat, just do it. I have to admire these bushes some more.
These quests are often the bread and butter of an RPG, but why? Why the hell would you run off and do someone else's dirty work? How heroic is picking up a book some idiot left lying around? Not at all. You're saving the damn world. You deserve to be treated better.
You might say, "But PsychicToaster, there are plenty of these quests that feel important and make sense!". Sure, there are. If you like being an errand boy. go for it. But at least make sure the errand is actually meaningful...and for god's sake, if it's another "in a cave to the west there is a UBER MAGIC ITEM THAT WE NEED TO STOP THE BAD DUDE!" I'm uninstalling. Stop leaving your omnipotent magical artifacts lying around for any idiot with a sword to pick up. Another thing; if you knew this already, Mister NPC, why haven't you retrieved it already?
Make fetch quests worthwhile. They should be more than mundane tasks, they should be a part of their own story within the world. Even if the quest is fairly basic, at least try to make it more exciting than killing five creatures in the woods(or 30 if you're doing random battles) and picking up some iron bars because the blacksmith suffers from memory problems and somehow forgot he left them there.
Go Tell Somebody a Thing-We've all seen it before. The mayor is dealing with a lot, and needs you, a man he's never met, to deliver some information to his Captain of the Guard. It might be of sensitive nature, it might be because he really needs to berate the Captain for not dealing with those mischievous miscreants that have outfitted the local wildlife with plate mail and fireball casting orbs, or it may simply be to play catch up, because as you know, the mayor is a busy guy. He doesn't have time for tasks that are beneath him. His army of messengers? Useless. He needs you, hero! You're the only stranger in town he hasn't upset with a litany of ridiculous requests, and he'll be sure to unlock the West gate for your party if you do this. You know, that arbitrary barrier that has kept you from actually going out and playing the rest of the game. What a jerk.
Seriously, stop with this. I get it. If it's actually part of a quest line where you've been established as a trusted individual and one that can handle his or herself in the heat of battle, then cool. Deliver the message. Run as fast as you can to the hills and inform the troops camped out there that they're needed. The town is in danger, and there's no way it'll make through without aid. But telling Little Johnny that his mother needs a word with him because he's been shirking his chores at home and sneaking down to the Old River Bridge is ridiculous. I would assume somebody might be available to let the disobedient lout know he's in for a spanking.
An unestablished hero is not a hero. Nobody knows who he or she is. Why would people instantly recognize him or her on sight? It makes no sense. "HAIL HERO, I HAVE SOMETHING STUPID AND MEANINGLESS FOR YOU TO DO! What do you mean 'how do I know who you are? You saved that town forty miles down the road. I heard about it yesterday, literally a minute after it happened. For a hero, you aren't too bright!".
There's Some Bad Dudes Over There-"Hi! I'm a guard! My job is protecting the citizenry from outside threats to their well-being! I am well-trained, well-armed, and have a large group of similarly skilled individuals at my call! Can you go and kill fifteen thieves for me? I've got to stand outside this shop and harass children. They've been sneaking in and stealing all of the naked drawings of elves."
Just...no. Taking care of a threat that isn't a threat for the sake of doing it is not a quest. It is boring, insipid, and as demonstrated above, pointless. Something the guards could and should be doing just breaks my suspension of disbelief. If they're that incompetent, I fear for the town's safety. If they're lazy, they should be out of a job.
Again, these types of quests aren't inherently bad. It's the setup and the writing that makes them so. I can understand dealing with a dire threat to a farming community that can't rightly defend themselves, but having a member of a powerful military force send random people off to do their jobs seems silly. Or wrong. Perhaps you're more disposable than you thought. What a pack of morons. After you deal with the thieves, they're next, believe me.
I Can't Behave Like An Adult-another of the "go talk to X" quests, only this time, it involves a relatively childish or mindless conflict. So and so said something mean, Sally got pushed, and instead of contacting the authorities, letting bygones be bygones, or hitting the offender with a rake, the NPC asks you to step in and make things right. After all, master negotiators and experts in conflict resolution are often travel-worn and blood-spattered mystery men and women. Go on then. Go talk to Big Dan. He's waiting with three of his thugs, and despite the conflict not even involving you and your party in any way, you've got to fight and kill three mostly innocent people for a perfect stranger. Good job. Who is supposed to be the good guy again?
I can't stress this enough. I've said it several times, but why are we doing this? That's the point often missed with side-quests in general. There's a difference between doing something because it's important and makes sense to do so, but being literally unable to deny a request and abandoning all autonomy in the matter of resolving a minor conflict is absurd. It all boils down to reasons, expressed in the writing of your game. Get your player involved. Not just because they can, but because they should. Make it worth his or her time, draw them in, engage them. Even the quintessential Lawful Good character would get sick of this nonsense. There's no way he can handle another stupid request from a toothless villager. He's not a doormat.
Another thing to keep in mind is that side-quests should be wholly optional. Not "optional if you don't like winning", but actually optional. Unless they're a side-quest to the main storyline, which then might be necessary. But for god's sake, missing out on a gamebreaking item because you didn't do a side-quest and making the game more difficult for the player is a horrible move and bad design.
I'd like to emphasize that side-quests like these aren't bad. It's their delivery that is bad, the how and why of going through all this trouble. Please, for god's sake, make it fun and at least somewhat related to the fantastic world you're trying to build for your game. That's all I've got for now, because I think the point has been made. Revolutionizing quests in general probably isn't going to happen, and I'm not trying to push that. But they should be fun. Games are entertainment, not a job. They shouldn't feel like one.