It doesn't hold a candle to FFX but it is quite good, better than X2.

Music - Worse than X
Story - Worse than X
Game start - Slow, while X exceeds at it. I couldn't put the joystick down until Tidus got to Besaid. XII is like all regular games: drags on at the beginning
Game play - Better than X, battle system more slick, controls streamlined, gambits make leveling up fun... I just miss all the fun in-battle banter X had like Auron saying "This is how it's done". XII has just grunts and whimpers. Yuck!
Flow of missions / story - X is much better, unexpected but fun. XII is a bit weird and off putting. Hunting for a rogue tomato is one of your first missions. WTF ? Leave the cuteness to moogles!
Graphics - Better than X and that is saying something!!!
Overdrives / Special attacks - XII has some very cool "quickenings" up to par or better than X but the Special dresphere attacks at X2 were better IMHO.
Espers / Summons - Haven't got one yet
World - XII's world is huge!!! It wins over X in vastness, variety and graphics, though I do wish XII had some temples and hyms