We recently came into our third Dyson vacuum cleaner the other day (having owned a DC01 and a DC05 in the past). We chose the DC15 (the one with The Ball), mostly because we have two pooches and they tend to shed hair a lot.
Even though we'd been used to the Dyson cleaners before, the DC15 certainly gave us a run for our money. We cleaned an area of carpet that had already been run over by our previous DC15, and the result was impressive; it managed to pick up dirt that we couldn't even see! The power is certainly something to behold. The Ball is also relatively manouverable; though it takes a bit of getting used to at first (especially since it's heavier than the mini-DC05) but once you get used to driving it around, you can easily control where it's going. I think it's mostly useful for getting around furniture, and in some cases under things since the cleaner bar is thinner than on a regular Dyson.
The other good thing we've noted about the Dyson range is that they do keep on innovating. For example, new Dysons have a removable cylinder that hinges at the bottom, which makes emptying it a breeze. The brushbar tool also helps with getting rid of animal hairs off stairs, which used to be a bit of a bane in the past.
In all, I can highly recommend any of the Dyson cleaners, and the DC15 has proved no exception to this rule. If it's worth paying more for The Ball or not; that's probably more to do with the arrangement of your house than anything (or whether you like buying cool technology). The DC15 sucks, and sucks hard.
In other news, the Contrarotator CR01 has quietly dipped below the radar screens at Dyson. Apparently, they used to be made in the company's Wiltshire factory but production was outsourced to Malaysia; and then the increasing cost of fuel charges meant that they couldn't be economically transported back to the UK. So they're gone, but not forgotten; sometime in 2006, they'll make an appearance on the laundry scene again. Fortunately, ours is still going strong and will keep on rolling for some time.
Speaking of things that never made it, you don't hear much about the DC06 these days. Apparently, since the company has moved on from the dual cylinders of the DC03 era, the DC06 was canned. Instead, they tell me that they're working on the Root8 equivalent similar to the DC11 range. However, Dyson seems more interested in getting the uprights into the American market; over on holiday recently, there were several demoed in stores such as Macys and Sears. It may be a few years yet before the Dyson starts chasing the dog around the house...