I have a Dyson and like it. I got it on a sale before Thanksgiving for over $120 off so the cost wasn't near as bad. I had used one at a friends house and it worked well.
I had a VacMan, similar to a Rainbow before the Dyson. I really liked it because it doesn't use any filters (just the water) but my kids couldn't do well with puting the water in and setting it up. It was great though for accidents like throw up etc because I could suck it up with that, then suck up a quart of clean water to clean out the hose. I'd dump the water and do it again.
The vacman is like a canister vacuum and the motor head could go almost anywhere, in any direction, and really low to the floor. I really miss that in the Dyson. I have to get a straight shot or move chairs to get to crumbs and I can't get under beds without using the hose instead of the brush head.
I really do like the Dyson however. We have allergies and I love the fact that I don't have to buy HEPA filters every few months or so. The Dyson's filter is washable.
We have the purple Dyson with all the attachments. We got it for around $379 at BestBuy in November around the Black Friday sales. I'd been thinking of getting one for a long time but wouldn't spend the money. When I saw that....we went for it! Personally I do not use the larger attachments. I use the ones that attach to the handle. The mini head for stairs is obnoxious to me. The air flow makes it turn, so when you put it on carpet the friction can stop it from spinning so the hand tools work better for me on my stairs. Short carpet in a car might be better for that. My friend had the Yellow Dyson without all the attachments. If you find a sale on that one you should be good to get that instead of the purple. From what I remember from some kind of a review, the ball type is NOT one that I would have purchased myself.