We had a Dyson DC02 HEPA for a decade and it didn't impress me all that much. It sucked okay, one of the wheels broke, the head broke and needed replacement, the adjustment button for the telescopic broom fell off, and the handle broke. The cable retraction mechanism also failed. Oh yeah, and the cover on the back which held in the attachments stopped closing.

The worst thing about it was emptying it. The cyclone part would have lots of dust attached to it, hair would wrap itself around it and that means when you take the lid off you end up with a cloud of mess. You obviously don't want to be doing this inside, and when you do this outside make sure you check the wind direction! Then you have to get the stuff from the canister into a bag, attempting to 'seal' around it so when you turn it over dust doesn't fly out all over the place - this is practically impossible. Then you realise that dust is escaping out of those little child-suffocation-proof health & safety holes they have in the bottom of the carrier bag and onto your clothes. I'm not a fan.

Replaced it with a Miele S5 HEPA a couple of years ago. Seems more powerful, quieter, cheaper and better made. The design is great, the castors on the bottom make wheeling it around so much nicer than the Dyson. The adjustable power is useful and it really does feel completely solid and made of much better materials than the Dyson. The bags hold a lot of dust so don't need changing all too often, and they are not expensive either. Can probably get a lifetime of bags and still would cost less than a new Dyson.

Can't think of anything bad to say about it, I really like it a lot. Looks like you can get the more powerful S8310 Power Plus for 200 quid. HEPA seems like its a lot more though on their website.