FFXIII ultimately has a fun battle system, but you wouldn't know until about 20 hours in when it finally stops drip-feeding each mechanic. I wouldn't blame anyone for skipping the game given the glacial pace and charmless cast; the aesthetics alone can't be expected to sustain people until the game finally opens up.
My pick of JRPGs from the last generation is Resonance of Fate. It came out at almost the same time as FFXIII but stands in complete contrast to it, with layers of interlocking mechanics that are open right from the start. Naturally this places it at the other extreme where some will find it impenetrable, but it's one of the most mechanically interesting games I've played in years and is endearingly bizarre.