The Tower Defense style of gameplay is as fun as it always is - meaning you'll hate it if you don't like it on web-based games. You run around with your little Tiki-looking man and one-by-one turn all the trees into attack towers to defend your mushroom village from puffs, flying puffs, elephant thingies, bees, and other stuff. Oh, and Spiders. The spiders are bitches.
I have to say this: The mechanic of replacing trees with towers - each tower having its own firing radius - is interesting. You have to choose the placement of your tower carefully to get the most out your investment.
I think this has an interesting philosophical implication that PixelJunk could've incorporated into the gameplay as well. Each time you put up a tower, you're taking down a tree. In a particularly epic level, you might end up replacing ALL the trees with towers. Once you're out of trees, the only way to build a stronger tower is to either upgrade your current one or remove it and put down something else. I'd be interested to see if an environmental aspect could be incorporated into the game. Not because I dirty hippy tree hugger (I hate camping), but because I think the idea of replacing all the trees in the forest with buildings is an interesting one.
The local cooperative play is essentially identical to the one player, but the ability to coordinate coin-chasing, tower-upgrading, and tower-building with a friend makes the game that much more fun.
Gameplay aside, the graphics are incredibly cute. Not tiny-baby-kitty-with-a-big-head cute, but still cute. The art does't exactly all match up in terms of origin, but it meshes well together. For example, you play as a little Tiki-man, like I mentioned before. But then you build these European-style cannon towers and then later it escalates to giant flamethrowers and lasers. Despite that disconnect the art comes together to make a coherent whole and makes for a unique looking game.
I had purchased this on a whim from the PSN store during a sale, but it's quickly become something I look forward to playing every Sunday night for a bit.