I've got a MSR International and I love it. However I also have a SoloStove with the accessory kit (Swedish firesteel, Large chunk of fatwood, spirit burner, and wind shield) which I love! The advantages of the gas stove is that it is quick, reliable (if you take care of it), and clean - your pots don't get sooted up while cooking. Big disadvantage is that it gives off no ambient heat.
The Solo Stove
Pros: lightweight, burns biomass (twigs), very efficient, not dependent on carrying around your fuel (I will say that one is a fool if one uses this stove and doesn't keep a sack of try twigs and kindling in their pack in the event that conditions turn foul - also good to cave some extra denatured alcohol for the spirit stove which I only use if I'm really tired, conditions really stink, or I just don't want to bother with making a fire), generates ambient heat so you can warm up while cooking, and after cooking you can upend your stove and dump your hot coals to easily start a campfire
Cons: some places will not allow you to make a fire; pots get sooty and require cleaning (a little bit of a pain in the butt).
I have to say that I can remember camping up in the mountains of New York where the temp dropped a good 30 degrees F in no time flat and it was raining hard... And we were cooold. I would have given a lot of money to trade my gas stove for the twig burner.