Out of the franchise, this one is most like Crackdown, or if you think of Saints Row on even more crack than before. If GTA V gets a similar reception to GTA IV, where everyone loves it at first but gets slowly annoyed with its realism then I see some people still buying it.
I do agree though. I'm glad I bought it in the end however, cos it was extremely fun to play with some amazing references placed throughout, and if I had waited until after GTA V I doubt I'd be too excited to play it. Even if I am a huge fan of the first two titles.