I've been playing this game on couch split-screen coop since it came out and while it is alot of fun, we've experienced quite a few bugs that take away from this games charm.
Noticed Bugs:
-second player's belonging and skills are constantly getting erased
-going from one map to another often leads to both players missing items
-the map doesn't display the right area
-issues with dungeon teleportation devices glitching out that causes the player to go into a "falling" animation that makes it difficult to leave the area that is glitched or activate the teleporter
-getting stuck in areas of the map
If you plan on playing this game, be aware that you're probably going to encounter some really annoying bugs until some patches start flowing through. But if you have the patience to play through them, you'll probably really enjoy yourself.