Reviewers go crazy for gta. It's always been that way.
I'd rate 360's gtaV a 8/10. There are still things I dislike about the series.
Despite a budget which puts most big games to shame the combates still far from great (But much better than past GTA's). Trying to go from mission to mission can sometimes make the overworld feel like the most slugish and convoluted level select ever. It plays like a series of little peaks of great excitement doted through a repetitive, limited, and eventually boring overworld. I got sick of the game long before I finished it, but to be fair it is a large game. Though I liked the main characters interactions, and it helped me get drawn into the game and it's missions, the humour (Like with past GTA's) doesn't work for me.
I do think it's a great game (as I say 8/10). I am only stressing the negative here because of the insane love it gets.