I really want to buy this game, but i heard it ahs some bad bugs and really bad hit detection.
Has these issues been fixed or is there a unofficial patch?

The hit detection is mostly fine. It takes some getting used to but after you clear the first few levels it's fine.

I just searched whether there might be en Enclave bugs thread open already... I hope it's ok on these forums to "necro" old threads ^^

Are GOG releases guaranteed to always have the latest patched versions of the game?
Or can it make sense to look for patches with games purchased via GOG ?
(I'd guess not since GOG has DRM freed versions, so official patches won't work, but who knows...)

What's really annoying me with Enclave, especially after having played quite some levels, is that enemies can sometimes see me through walls, and worse, hit me through several pieces of geometry with their arrows, while I generally cannot "return the favor" !

This is really annoying and unfair, and even more so unacceptable looking at the fact that you can't save in this game... I get really angry if I have to do it all over, *again*, because the enemies can cheat ...