This thing might be cool in fair weather, but it's not a mountaineers tool.
THE CONS: The hype about the pressure regulator making the fuel run more efficiently is total bull. If the canister is sitting in snow, the stove quickly weakens to a whimpy simmer which make snow melt times pathetic. When they say not to use it in a tent, they aren't kidding either, mine belches a 24 inch fireball every time I light it. Don't set the the pot down in the snow or the integrated heat exchanger will be packed with snow. Don't boil over either, the exchanger funnels water (or in my case hot coco) down into the heating element. No auto igniter on these puppies, which might be nice when you don't have a lighter handy. Finally, the actual stove assembly can't be set in the snow either. Getting snow in the element or in the IsoPro fitting makes the stove inoperable. Oh, and Iso is expensive!
THE PROS: In warm weather, the stove rages! Mine boils a quart of water in under a minute. The pot is nice and big too. I can fit two Tasty-Bites in mine at a hard boil. The little pac-towl is handy, and the rubber knob on the lid can handle a fair bit of pack crushing.
Overall the Reactor is useful for fair weather camping, but when the snow flies, leave it at home.

I bought a pair of these last May. Since then I've worn them to the crest of the Andes, several sierra summits, and worked and lived in these shoes. They are an awesome all around light shoes. But they do have problems. Being waterproof-breathable, they are actually neither. Out of the box they cause your feet to sweat in any moderate climate, and tend to grow that wet gore-tex smell. After about 150 miles the main flex point at the ball of the foot wore out on mine and turned into little gills. The rubber rand became a small cup for water and sand and the gore-tex wore through in striated wrinkle lines. So by July I had shoes that weren't waterproof but breathed nicely. The other gore-tex areas of the shoe can hold up to the occasional light splash of snow or water, but any sustained precipitation saturates the shoe. By the end of summer the soles had begun to de-laminate seriously, but managed to hold on through most of the fall. I continued to do stupid things with these shoes, like lots of chainsaw work and dumping glowing coals on my toes, through january, when the internal structure of the shoe broke and carved a significant hole in my pinky toe during a short run (pinky space was always an issue). So they made it about 9 months to total failure. I haven't hiked in them seriously since September. I think I'll buy something with more durability next.