I'm finding the game good so far. I didn't follow any hype whatsoever because I didn't want to be disappointed but when I first got it I found it a bit of a let down. Every GTA so far has been quite a step above the last one, including 4 even though it missed a lot out, but this one seems a remake of the last one with a bigger map (although the maps not actually as big as people seem to think, especially if your used to playing RPG games) and more stuff to do.
I did get into it though and i've been enjoying it. In previous GTA's there doesn't always seem to be a purpose or a motive to the missions but this time I find it much better laid out. Although I agree Frank is boring and Trevor inconsistent and only there to serve the role of resident nutter, you do get into the characters, especially I find Mike, which always seemed to lack from the other games.
My big problem though is that the game is too short. I'm, not far from completing the story and I haven't actually been spending that much time on it. I don't think i've ever managed to finish a GTA game, and if I did there was still so much to do it never felt like it. But this time I reckon when i've finished the story ill be bored of the game too. Having replayable missions seems a bit of a cop out to me instead of adding more, a bit like COD will let you complete the story and then expect you to replay missions to extend the game life, its not good enough, especially from Rockstar. I understand how much effort and time they've put into the game but I think maybe more should have been spent on extra missions for the characters, either separate to each other or as a group....
Oh wait they'll sting us for that when they decide to release some DLC in a couple of months....