The Mach 3 demonstrates excellent carpet-cleaning power, at least as a new vacuum, and if it maintains its performance (I've rated its durability as average simply because it's new) it will be a remarkable value at Walmart for only around $90 with an extended warranty, no less.
I bought this vacuum because it was under the $100 price point yet has the cyclonic suction I was looking for, as well as the economy of all-washable filters and bagless-ness. If you've seen Consumer Reports, you'll note that there are several very cheap and highly rated vacuums that use bags, but however arguably Dyson's machines function, he's absolutely right in his critique of old vacuums. Changing expensive bags that drain suction almost immediately is tedious, costly, and outdated.
Here are a few cudos and caveats:
1) It is a heavier than normal vacuum, which I personally prefer because the weight helps the brush raise the nap of the carpet, which is one of top two most important things to me in vacuuming the rug in the first place. C'mon, people, it's on wheels, for crying out loud. Use the muscles God gave you!
2) There are two minor design flaws, one trivial, the other important: The hose/pet attachment is awkward to use, even with extension wands. I find myself lifting the vacuum to get easier access to the vacuuming area, which some would find difficult to impossible, and that leaves no hands free to hold down a throw or area rug. The designers seemed to have predicated using the pet attachment only for the floor. Well, if you have a cat that is the least of your vacuuming problems. Second, very minor, the angle at which one normally vacuums throws the light up too far, not to the area right in front of the vacuum, so it's not very useful. You'd think someone would have seen this somewhere along the design road.
3) The vacuum doesn't emit noticeable dusty odors during use, but I'm not terribly sensitive to that issue, and think that was a neurosis invented by manufacturers of bagged vacuums (I've owned them too and see no difference in the dustiness of the vacuuming atmosphere); anyway, it has three filters, and each can be cleaned.
4) I have used it on the next to lowest-level setting for several minutes at a time and the engine has not shut down due to overheating, the problem with my old Mechwarrior-reminiscent vacuum, even though it performed only half as well as the Hoover. That tells me that the filtering system is designed well to not clog immediately and overtax the engine and the engine is sufficiently robust overall.
5) Cleaning the main cyclonic filter is awkward. But I suspect that when I perform the operation more and more it will become easier. The first time one fears doing it wrong and breaking it. Still, the instructions could be better on that operation.
6) Assembly was a not difficult. I think the telescoping handle goes up and down a little too stiffly. I didn't think I would care, but I do like the power button at the top of the handle.
By the way the Mach 3 model is not reviewed by Consumer Reports, but it liked the more expensive Mach 5 well enough.
And here is my final overarching shopping tip about vacuums, which some might find very helpful. There is apparently no vacuum in the world that isn't rated by some consumers as the best they've ever used or the worst piece of junk they've ever bought. So let common sense prevail. Good luck.