Don't get too comfortable waiting for the water to boil. This stove is by far the fastest I have ever used...bar none. If your goal is to boil water, look no further.
I bought the MSR Reactor after a winter backpacking trip to the top of a cold, windy mountain. My reliable, compact SnowPeak stove wouldn't work. I bought the Reactor so I wouldn't have to put up with cold soup and iced chocolate. The trade-off of a slightly bulkier stove/pot for for the high reliability was worth it.
[1 of 1 customers found this review helpful]
If all you want to do is boil water, you have to look hard at this stove. For that, it is awesome.
It takes no time to set up (from pack to full flame in under a minute), and they aren't kidding about the fast boil times. About two weeks ago I boiled a liter of cold water (both the water and air temp were 42 degrees) in under 3 minutes.
That said, it is so hot, I don't think I'd try cooking anything in it. Mine didn't come with an ignitor (not a big problem, I always have a lighter with me).
It's not ultra-light, but when you consider the massively increased fuel efficiency, it could well be lighter than any other option. Much depends on how many you cook for (one stove could easily service 4 people) and how long you tend to go out for. Do the math before passing on this one for weight reasons.