Everything except pricing information and independent verification of their superiority claims. Dyson's have traditionally come with a premium for their "technology". I'll be patiently waiting for the reviews to trickle in.
I have a cheap Roomba iRobot and I'm perfectly happy with it. I have hardwood floors so even if the Dyson has more power, I do not see a compelling reason to upgrade.
Why "technology" in inverted commas? That's an unwarranted sneer.