This is something that hasn't been done before, and has a lot of exciting possiblities. Being able to choose your own attributes can possibly cause a disruption in balance, but that has yet to be proven. As far as I've seen, there isn't a whole lot of difference in the switching of attributes except for the ability to use certain weapons, which is in trade for resistance and speed. This adds some fun to it, giving you the configurability to have what you want, but the balance is still there. Here's the sweetest part of the peach.
Most weapons have an alternate method of firing, and there are several classes of weapons.
From the usual shotguns and autmatics, to the Death Ray and Singularity generator, and even past that, to the VooDoo Doll and Phantasm Ball. The one weapon which seems to rule the game has got to be the Howitzer. Akin to the Rocket Launcher but with instant damage and slower reload time. The sniper rifle again has a great effect, and gives the campers something to smile about. Although the damage is doubled, so is the ammo depletion.