After using friends DragonFlys in the backcountry for years I finally got one for myself. I have used a cartridge stove (Not sure what brand, I've had it since I was a kid) and have always liked the liquid fuel stoves over the cartridge style due to their versatility and the fact that you can use a wind screen as well as the stability of this stove in particular.
The DragonFly is amazing in the winter time for melting snow and uses a very small amount of fuel for the job (over a hr. on high per 10oz of fuel) and takes no room in my giant winter pack. For summer, it's a bit bulky but I like the fact that you have solid heat control and can bring foods to a simmer (great for beans and rice based dishes).
In real world conditions the stats given by MSR are a bit unrealistic but here's what I have found to be the average; 45F outside with a 10-15mph breeze at just over 7,000 ft., you can bring 3 � cups of water to a rolling boil in right at 3min 45sec (by the way, it works great at altitude also, lighting right up at a bit over 12,000 ft.). I used a GSI tea kettle for these tests and this was consistently the numbers I got (give or take 10sec either side on average). These numbers were with the wind screen and reflector that are included with the stove. For small pots (narrow based solo sets for example) you will need to jerry-rig something to narrow down the pot stand (I use tent stakes propped between the legs and have had no issues with stability).
Now as far as the noise, it's true that it's pretty loud (reminds me of a small jet engine) but this is only the case when it's on full blast. When simmering the noise is on par with that of your typical liquid fuel stove. If you're looking for quite, go with an alcohol stove (which I also like), if you want something that works with pretty much any pot and gives you the most control over the flame level (and a lot of heat when you need it), then this is the stove for you.