It's hard to describe my feelings about Final Fantasy XIII. On the one hand it's horrifically slow to get going and does pretty much play itself for the first few hours. On the other hand it features possibly the most likable cast of any FF game to date (Pedobear approved Vanille excepted), has a brilliantly paced story and a battle system that starts out simple and grows to become insanely deep. When I can spend hours in the menu tweaking my paradigms in preparation of an upcoming boss fight then I know this isn't a simple system. I've heard people bitching and moaning about the Auto option on the battle menu but the stunning thing about that is that A) the auto commands are usually stuff you were going to do anyway and B) you don't have to use it. There's an option in the settings menu (which some people are genuinely unaware of) which lets you set whether the cursor defaults to Auto or to the Abilities sub-menu. Selecting lots of different abilities is very useful when you're trying to fill up a Gestalt gauge during a Eidolon battle. Bottom line though is that FF13 takes a bit of time to get going but once it gets into its stride it's right up there as a great game.
Also don't bitch about the game being linear, FF10 was one linear path from start to finish.