The InsulMat Max is the lightest thickest mattress I've ever seen. Weighing just 22 oz, and being 2.5" thick is quite an accomplishment. This replaced my old Thermarest 2" pad, and is thicker and lighter! It does loose the ability to self-inflate though, and being so thick, it does take quite a few breathes to inflate, however, unlike previous non-self-inflating air mattresses, it does have insulation (in the form of what essentially amounts to sleeping back insulation in the air tubes). I didn't test it in the snow, as its rated to 20 degrees and who knows what that means, but for summer backpacking, its perfect. The pad rolls up to less then half the size as my old mattress which makes it easy to pack and when inflated it is very comfortable.
Compared to a foam pad, it is heavier, but infinitely more comfortable, however I would recommend a foam pad if where you are has sharp rocks (or other items which could pop an air mattress), or if you are camping on snow (or on very cold ground where you may need the insulation.)
Compared to a self-inflating mattress, its generally lighter (even then full length 1" thick ones) and thus more comfortable, however, if you don't need this much comfort (I sleep on my side, were i to sleep on my back, I'd have a 1" mattress (although I'd probably go foam for weight). Also it does require inflation and unlike the down equivalent, it doesn't come with a pump so you have to blow it up, I don't find this a problem, but you usually don't (or at least not near as much) with a self-inflater.