Parts:
It's an impulse set, so really, all you are supposed to get is a fig and a handfull of pieces with varying uses. I guess this is as good as any in that respect. A troll like any other, a rat, some wheels, and the spears. So-so.
Design:
Horrid, just horrid. It's Lego's typically flimsy attempt to create some "moving parts" as it were. Having yet to realize the lack of coolness such things bring to sets (just look at any set with a "catapult"), Lego went ahead and created another of their wacky, weird and ugly wagon-battle-attack-thingys. What actual siege weapon it is supposed to vaguely represent is something I cannot begin to guess at. I guess Lego just thought their flick-fire thing was so cool and tried to put where ever they could. Fools that they were in this respect. The only thing flick-fire has going for it is that it isn't a catapult.
Playability:
The flick-fire thingy aside, it's a bit meh. As I said, it's an impulse sets, which is basically a cheap way to get a fig (I use the term "cheap" in relative terms). And as far as that goes, the fig is a great fig to play with. I'm sure all the 6-12 year old kids have enjoyed playing with the troll figs, so a thumbs up here.
Dan

I build, therefore I am.
Brave words coming from a guy called grapenuts.