With such fast paced gameplay, it took a bit before I figured out how the combo system worked. Once I realized how it worked, the colors on the weapons matching the top combo requirements was very nice and made getting the easier, when the right ones dropped. The combo system is an interesting mechanic for advancing waves, and not one I've seen before. It really changes how you think about what weapons to pickup.
I enjoyed trying out each of the different weapons. There was a nice variety of options, and with such limited ammo, you were strongly encouraged to experiment with them all. I initially wasn't sure about melee, but with unlimited ammo, and a pretty big range, it was surprisingly effective.