I ordered it for PS3, maybe we are being pessimistic but I think i'll get bored too. The PS2 GTA's were all flawless and fun and had cool stories imo.
Not pessimistic, GTA games are fun but the problem is it's the 5th in the series and unlike some series like TES/FF and a few others that stretch the series far, you drive around in generic cities and do mob/criminal missions (every single game without variation between entries), and the whole "I'm a criminal in a city" theme is just very played out and straight up boring to me at this point.
The game will be good on a technical level, it's just tiresome for me. But Co-op will make it more fun as co-op makes any game more fun. That's not to say that other series like TES/FF don't make other people tire of them, it's all just how much you like a theme/game style, and GTA just isn't my thing (unless co-op hopefully).