The character/creature design worked very well with the environment, I thought. I don't really know what to say concerning this, except that it was good.
Gameplay can potentially be very varied, or it can be pretty samey all the way through. All bounty missions have multiple ways to get to and capture the bounty, either alive or dead, and doing this is lots of different ways gives a lot of variety and replayability. There were a lot of fun inconsequential things, for example, a real-time movie may start where a couple of outlaws blow up the bridge you're walking across. It doesn't do much except create more entertainment. Or where a couple of outlaws will blow themselves up in a real-time movie a couple of hundred feet away. Doesn't mean anything, but it's fun.
On my second go through I used the live ammo more.. economically, disabling enemies as quickly as possible. Overrall, the live ammo is very well implemented. Each of the live ammo will have nests around a particular area and will scurry from one to the other. If you move to close to their 'path', they'll all run the other way and hide in the nest. It's very good. A couple of ammo types felt a little redundant at times, such as the stunks which I seeemd to only use just because I hadn't used them previously - not because I thought it would be more advantageous.
Spark Stunks are a different matter and must-use once you get them.
In terms of the design, there were a couple of elements I wasn't very happy with - the clakker architecture and some of the vehicles, such as a stationary yellow school bus. I had expected a lot more barrel shaped clakker buildings, but they seemed pretty normal.
Edit: It also feels very alive. You might be attacking someones base, and they won't know you're there, and the boss-man might be shouting to his minions over a mega-phone about really irrelevant things which just adds to the aliveness. Clakkerz will randomly talk to each other about you, as will grubbs and it's really cool to listen in to their conversations. There are also quite a few genuinely funny moments, and not just in dialogue.