Before I go on, I'd like to say that the reason why it isn't just one post of criticism for me but many more is because I've grown up loving this series (well the fag end of growing up years I guess), and hence it is important to me.
Ultimately it's just left me a bit confused.
The world is clearly fantastic and there's a great deal of content and effort put into it which deserves plaudits. The technical aspects of it are huge jump from the previous editions as are things like character animation. I love how every character has a different animation style, it makes it so much more real to take control of different ones. Flying a plane feels awesome. The underwater stuff is a nice addition and generally everything is a nice big upgrade from the previous GTA. Also, I agree that this one brings the fun back. The humour is better and less held back than GTA4 which tried to be more gritty and sometimes forgot its sense of humor.
However, there's two things that, for me, keep me from really loving this game.
Firstly, the story is a bit drab really. After what I thought was a poorly done first mission, they do a nice job of introducing the characters to you and there's a nice freshness to the game. The multiple characters system works pretty much flaulessly. But once your characters know each other and their story "together" truly begins, it sort of meanders out into directions that are, for me, completely uninteresting. The FIB stuff was bullshit for me. I was just dying to get it done with, and sadly, it WAS the main story arc of the game. Devin Weston and Merryweather too were a nothing entity. Boring, generic bad guys who were hard to give a shit about. Compare that to San Andreas storyline of betrayal by friends, and revenge on a bully. Sure, you had one sortof "emotional" side with the whole Brad shit that happened ages ago, but does the gamer actually care about this whole bad blood between Trevor and Michael? I mean they spent most of the game bickering about it like a bunch of children and there was nothing to connect to really. Who gives a shit about fecking Brad?!?! Also the ending had to be the most obvious thing on this planet. Franklin was in the end so often stuck in between the two bickering women, and his role was completely reduced to a "just stop it, dawg" puppet, they were always going to give him the choice over everyones fate, since he was the "neutral" one.
Secondly, the missions themselves could have been so much better. All of them seemed to focus on what youre doing rather than how you do it. There was no difficulty to them at all and no nuances to them apart from one or two where you could go stealthy if you wanted to. It was all just a simple point A to point B thing where the only thing that mattered is how things develop once you do it rather than how you get from A to B. The fact that the mechanics arent particularly brilliant doesnt help either but when a game is of this scale, it's okay for the mechanics to be a bit simple.
Overall, I just have mixed feelings about it. It's good fun like all GTAs, it's huge, it's full of content, but the two things above just hold it back from being something I can say is truly brilliant. The worst part is, I want to rate it, because I've always loved this series. So much so that I feel I should give it another go. But yeah overall as of now, I'd give it an 8.5/10 to 9/10 or something like that.