I don't know anybody personally that's put a significant amount of time into it and not really enjoyed it.
The only people I know that've not liked it, only played the first couple hours, complained that it was too linear and dropped it.
The paradigm system is one of the most intense battle systems in any RPG that I've ever played. Sure the game takes a while to open it all up, but the sections leading up to that get you to use different paradigms that you wouldn't normally think of, and might be crucial later on in the game.
Thing is, I've played through FF6 and FF9 following 13, and they're just as linear. Neither game really opens up until at least the halfway point.
That said, they were all games that I really enjoyed.