My second favorite Final Fantasy game (after Final Fantasy VI), it has an amazingly well realized world with lots of attention to detail, a fun strategic battle system (and some actual difficulty), a likeable cast of characters (well, excepting Vaan and Penelo, who are just boring), fantastic dialogue direction and voice acting, and tons of side content.
Everyone always seems to be down on Vaan and Penelo. I probably was too back when I first played it but replaying it now as an adult I realized some subtle nuance about the game's plot and characters that I missed.
Vaan and Penelo's purpose in the plot is that they represent the small normal commoners who are pulled and tugged by the whims of those above them.
PSN:Forevercloud (looking for Soul Sacrifice Partners!!!)