This was my starting point: I have a multiple dog and cat household. The cats in particular shed a LOT of hair. I have mostly wood floors but some area rugs and a carpetted stairs. I can end up with tumbleweeds of animal hair if I am not conscientious about vacuuming. I was ready for something really effective that I hoped would cut my vacuuming time and take a lot of the elbow grease out of the process.
I spent a fair amount of time researching vacuums and considering whether I really wanted to invest such a significant amount as is called for in buying a Dyson -- you can get a desktop computer for the same price!
I also weighed up numerous reviews and people's personal comments on various discussion boards because I wanted a good sense of how comfortable this was to use, how effective wih animal hair, how portable (as my house is small and storage space is at a premium), and how likely to have problems.
Some initial reports did say that Dysons had a higher propensity to break down, but I understand that was more when the Cyclone technology was first introduced and was more fiddly. (on the flip side, I am tired of the throw-away mentality of dumping things when they break and I know you can definitely get a Dyson fixed, mainly because they are costly!).
I've now had my Dyson for about 8 months and I would give it an A+ rating. My old small and very cheap Siemens vax had very good suction but it was a pain to find bags for it and they filled quickly. That meant the suction quickly declined and it was much harder work to get hair up.
I do need to empty the Dyson after every use, but the suction never varies -- always good and strong. That alone greatly reduces the hard work of getting stuff up out of your rugs and the floor. The HEPA filters also are fantastic -- they really keep dust -- to which I have an allergy -- at a minimum. No more sneezing when vacuuming! I simply do not any longer see little dustmotes everywhere in the air as I hoover.
Given that the unit itself is quit heavy, the vacuum is fairly maneuverable and has a very long cord -- a big plus so you don't have to keep unplugging and moving the vacuum. I like the rotating head that helps loosen and sweep up animal hair in particular -- this is one area where I really do see a difference in how the vacuum functions on rugs and carpets.
I also like how there are no really long pieces to the Dyson -- everything retracts and can be set to a comfortable length depending on your reach, then stores easily and compactly. The head also easily goes under most furniture, and I have found the smaller tools for sofas and curtains and blinds really work nicely.
To me, the Dyson is kind of the Virgin Airlines of vacuuming -- it is stylish and fun and makes a chore a bit more enjoyable. It will take a bite out of your wallet but I have been very happy with the return on my investment.
NB I don't think the cannister model of the Animal is available in the US yet.