Don't try this without friends, you'll go mad in singleplayer. Extremely difficult, we've spent over an hour on certain trials (still not done with all of them), especially difficult if you want to do the challenges. Controls work great on a controller, gameplay is overall interesting. The orb idea is a neat one, makes for fun and interesting puzzles, although you might kill your friends over it at certain times. You WILL have to go back and revisit previous levels to do the challenges, which provide the upgrade gems for abilities. I personally like this, challenges are usually fun and they really need teamwork, but I imagine it may bother some people playing the same levels over and over.
Plays best if you have friends over, you really need to communicate (yell, actually). The main reason why you really need friends for this. Everyone should have a mic and lots of patience, really difficult to have this with strangers.
Got a 4 pack in sale a while back, money well spent. We're at roughly 23 hours so far and still has a lot to offer, so I'm pretty sure you would be happy with it even at full price.