Played the PC version, beat it on Medium difficulty. It was okay. Yes it looked gorgeous even on low settings and the platforming was interesting at first, but it just got repetitive. Same with the enemy variety. I also thought the "bosses" were underwhelming (I evaded the toad-like creature until I realized I could shoot it in the back with the Thief from the high ground). The last level and the ending were terrible; almost like Borderlands in the lack of payoff. The camera worked well most of the time but sometimes I had to fight it.
The puzzles were pretty easy and at a certain point I would just triangle-grapple everything so that removed most of the challenge. The physics worked well most of the time but would also be frustrating.
Not only that but it also makes it more challenging. When in single player you only need to clear obstacles once and you're probably doing it with the character best suited for it (thief most likely thanks to the grappling hook).
When you're playing co-op you have to work with your partner in order to clear an obstacle or defeat an enemy. I've played so far with three different partners and it's always felt like a different game. I still need to get a whole party to do the full co-op (three players), it should be awesome.
Yeah, the game doesn't have much in the bosses department, and there aren't really "puzzles", just obstacles which need to be cleared, but it was very fun for me. I'm looking forward to Trine 2, day one.
Most people didn't like the last level because they thought it was too hard. Which it wasn't I thought the last level was a great little test of all the stuff you've learned through the game. I also thought the ending was funny and fitted the lighthearted story.
Also, getting all the hidden collectables actually made the game better as well, since it forces you to do a lot more platforming.
The levels (except the last one) are kind of sandboxy, in that just beating them isn't very hard, it's more about making your own fun.
The game needs more love. I bought it a few days ago with the Frozenbyte Humbled Indie Game Bundle and since yesterday, I'm through it. Great gameplay, great sound, great graphics - and overall a fantatstic game.
I rather enjoyed Trine, but hope Trine 2 becomes a major improvement on it (and have less tedious trophies). Didn't bother Platinuming it but I did manage to get most if not all of the Silver trophies.