Very quiet and functional! Worth the investment!
I have owned a MSR Dragonfly for 11 years and decided that it was time for a new addition. When it comes to cooking, my backpacking trips mainly include freeze dried meal and hot chocolate. The Reactor is perfect for this. My Dragonfly always sounded like a jet was about to take off. The Reactor is MUCH quieter and boils water faster in my opinion (particularly if you include setup and take down into account). The pot with which the water goes into is bigger than what I would normally carry and I had my doubts. When comparing the two stoves, carrying my stove, fuel and pot in 1 container is much more convenient than the 3 separate items I had to dig around for with with Dragonfly. I will probably still use the Dragonfly when altitude is an issue but I would say that the majority of my treks can be handled by the Reactor. There are 2 things I will suggest: 1)You will want to use an additional little towel besides the one that it comes with to wrap your fuel canister so it doesn't bang against the inside of the pot and 2) I wish MSR would make a deep dish plate (or bowl since we are talking about a 5" diameter) that could fit inside the reactor pot because there is still space that needs to be maximized. MSR's Folding utensil folds small enough to fit inside as well (you could fit more than 1 if you don't like using a spork).

Terrific and versatile stove
I picked up the reactor stove maybe two weeks ago and already am in love with it. Once upon a time I thought that a gourmet stove was the only way to go (MSR Dragonfly for example), but the more camping and backpacking we do the more we come to rely of freeze dried food. This simplifies the process as you need boiled water. Well, the Reactor boils water real damn fast. I am not one to time things, but it boiled enough water to make a two person meal and have left over water for tea in the time it took me to get out my bowls, sporks, get the food packet open and clear a place to sit down and eat. It packs down really well and reduces the need for multiple bags of gear (stove, pump, fuel, support base). It's lightweight and very easy to use. In short I love it!

Leave All The Other Ones At Home!!
I have tried a few different backpacking stoves - including another MSR model - and I can truly say that the Reactor is the real deal. It is very light, holds a sufficient amount of water for most cooking tasks, and boils water very quickly. Admittedly, it is a bit larger than some other models on the market, but, on balance, the extra size (which isn't all that much) is well worth the added performance.

Best Stove System But have some deficiency
The Reactor looks like the best option in the world for melting snow. But is the few minutes of time saved worth more than twice the cost, +6oz of weight, and loss of capability of using other pots? Probably not for me. And a critical flaw IMO, the Reactor burner does not attach to the pot so it can not be suspended in an alpine tent, easily held or served while heating, etc.. also It make CO,should be very carefully.

Just what I was looking for!
I purchased this stove because of all the good reviews it received. I am not disappointed, it's compact, easy on fuel and durable. I have purchased other MSR products and have yet to be disappoited. The fast boil time is no joke!