I have two questions:
1) Does the game ever get more complicated than auto attack with your choice of three positional special moves on cooldown and an additional ultra that comes online now and again?
2) I know that the various games in the series had slightly different combat systems. Are any of them actually good? Or is it all just MMO-lite crap?
Yes, you will eventually have an additional 3 master arts linked to your existing 3 for a total of 6 per character. You'll unlock lots of classes with very different sets of arts, skills and talent arts to carry over to other classes, so you can build semi custom classes that way. You also unlock Ouroboros forms with their own skill trees, as well as chain attacks which can be surprisingly tactical despite their simple premise. Noah also get a couple custom things to spice things up.
The game starts off very barebones and takes a fairly long time to unlock everything for you. Given that it's a very long game, I didn't mind this. Overall I'd say they got the complexity of the combat right which in addition to never ending party building optimization tickled my 'tism.
The earlier games have comparatively simpler and yes, MMO-lite combat systems. Both 1 and 2 have elements of 3's but stripped down. X does its own thing and is more complex than those two. It's the system I look forward to returning to after having played all of these games since it's not just a lesser version of what 3 had.