The dyson works very well. The key is that it's bagless so you can empty it as needed and as they claim, it doesn't lose suction.
The animal attachment is just a part that clips on to the end of the hose so you can do stairs and harder to reach places (furniture, etc). The only unique part is that it has a 'brush' that moves like a regular vacuum only it's part of the attachment.
So, having owned the Dyson for about a year now, I'm very happy. However, the belt is not user replaceable, it has a ratcheting system that alerts you to when it's having trouble which requires you to clean out the rollerbrush assembly. I have to do that every other time I use the vacuum.
I've had to clean the animal attachment thing once so far, as it stopped spinning efficiently. That was not a user-maintenance type activity, and it took me awhile to figure out how to disassemble it to clear it out.
Outside of that I'm very happy and I would buy one again if it lasts a few more years.