@JJK 42
I'm glad you couldn't post that image actual size, it's huge. There's no need anyway, as it comes up full size when it's clicked on.
Some factors to take into account when thinking of using a map like that. It is very large and complex, so difficult for the player to navigate, though you do have the main path clearly marked, which is good. How far into the game will the player be? If it's near the beginning, and assuming a reasonable distribution of enemies, it may be way too much. If it's later on in the game, it may be a bit easier - though again it would depend what you're doing on encounters. Next, why am I doing it, what are the rewards for exploring something that big? Is it plot related? Do I get really decent items/gear? I would hate to battle all my way through to the farthest corner only to find a couple of level one health potions (this has happened to me, so I know what it feels like). Factors like that have to be taken into account when judging the map, and as I don't have that sort of info, I'm reluctant to give a too definite answer to your question about it.
As a general rule, and speaking now as a player, I think there has to be a positive reason for having such a complex map in a game. It might be something like the reasons in the first paragraph of my answer, or it might be the overall style of the game, but if it's just a one-off "hey, let's have a big map", I think it rarely works.