I have two Dysons
A model DC07 All Floors, and a DC14 All Floors. They are not the best cleaners I have in my collection, but they are far from the worst too. As far as bagless goes, I generally prefer bagged machines. Besides the Dysons, I have two other bagless vacuums. One is a Eureka Altima, and the other is a cheap Kenmore canister. The Altima is a PITA to empty and needs a lot of maintenance, however as with anything else, if properly maintained it performs well. The Kenmore is useless. The dirt cup is so small, it needs frequent emptying in use. The filter in it also is useless. It plugs up so fast, and suction drops so fast, that I have put this machine away and never use it any more.
As far as the Dysons go, I find that if someone absolutely has to have a bagless machine, then the Dyson system is among the best. It has two filters, a pre-motor filter that is easily checked and washed, and a post motor HEPA filter that you are never supposed to have to clean or replace. When I got my DC07, I bought new filters for it simply because I didn't know what kind of environment it came from, not because I had to. The HEPA filter, while it had some dust was in very good condition. Even though I changed it anyway, I kept the old for a spare "just in case". I also like how easy it is to check and clear clogs in the machines. Since I got my DC14, I hardly use the DC07 anymore, and a good lady friend of mine wants a Dyson so bad, but she can't afford to buy one. I think I'm gonna surprise her tonight and gift her the DC07. Hope she likes it.