As much as I've enjoyed the little I've played (stiiiiiiiiiill waiting for that PC release), it does cement my belief that Rockstar's vision of how to make open world sandbox games is different from what I really like doing in them. And I don't mean that in a "this is right, this is wrong" way, but more just in the style. Rockstar really go for scale and density, and this shows in GTAV. They've poured all their resources into making a fucking gigantic monolith of an open world with a ludicrous amount of detail and activities, and have executed the whole scenario very well.
But I guess, end of the day, I do prefer smaller sandboxes if that means the core mechanics will be more refined and varied. This is largely why I loved Sleeping Dogs so much. The combat system wasn't a rudimentary physics based button masher. The driving introduced new mechanics, like dynamic hijack, that made it all the more fun. And I think this is something I really, really appreciate from the games I play.
I can appreciate what Rockstar accomplished, but there are other aspects of sandbox games I'd personally focus more on.
EDIT: For example, I think it's amazing the amount of customisation you can do to a car, but I just don't give a shit when it comes to my own enjoyment. I can see why people would love it, but it doesn't really enhance my play.