We have the Dyson Animal and while it's a GREAT vacuum and one of the best I've used, save your money and get the yellow one instead. The only difference with the "Animal" model is that it comes with the air-powered mini turbo head for cleaning your fur-niture. Doesn't work too great on our couches, although I admit I haven't sat down and experimented with it yet.
Other than that, it's a fabulous vacuum. Great suction, pretty damn good at rugs, handles pet hair like a champ. We have so much pet hair (and I don't vacuum every day... :rolleyes ) that I have to dump the canister twice before I'm done, but that's a minor nit in my opinion. It still cleans a damn site better and easier than 99% of the vacuums out there. And yes, the whole "doesn't lose suction" is pretty important when cleaning pounds of pet hair out of the carpets. Just keep half an eye on the hair level in the canister. When it's time to empty, I just hold it over our large trash bin outside, open, and whack it on the inside of the bin. Everything just falls out and everyone's happy
Honestly I don't know if I could go back to bag vacuums now. I grew up with a Kirby and had one myself for a number of years - GREAT vacuums, incredibly well built, but heavy as lead and changing bags just sucks. Canisters are the way to go, especially one that works this well! Just do have a place you can empty the canister outside, as emptying it inside will have the same effect as throwing a vacuum bag in the garbage then stomping on it