Just to second all the great reviews, I love my Optimus Crux. I suspect I have one of the older versions with a little wobble in the burner but great flame control, and I'm opting to keep it. The wobbling is a minor annoyance, but once you're aware of it you shouldn't have any problems.
Tiny, powerful -- what more could you ask for? It fits best on the 4oz fuel canisters -- the 8oz canisters stretch the elastic on the case a bit too much, and the case swamps over the sides of the smaller canisters. But they all still fit together in one way or another, and with a little ingenuity your entire mess kit will fit inside one pot with this stove in your arsenal. I've taken it on numerous backcountry outings, and it now comes highly recommended by me.