It may not seem like it there has been much change, but the 800 series and later Roombas are vastly better than the older models. I had one of the early 400 se

It may not seem like it there has been much change, but the 800 series and later Roombas are vastly better than the older models. I had one of the early 400 series and it was problematic: it required a lot of picking up and it would get entangled on cords, carpet fringes, anything loose. It also would get stuck and the brushes would get jammed up with hair. So while it vacuumed ok, it required so much picking up and fiddling with that we gradually stopped using it. The new 805 we got at Costco (a bargain too) looks similar overall but everything is different in detail. The new rollers don't get tangled, it doesn't get caught on cords or fringes, it slows down and approaches walls cautiously instead of just crashing into them, and the algorithms for getting unstuck are effective. Now we have it set to run unattended twice a week and the house is cleaner than it has been for years. I recommend the 800 series (or up I guess) over the 650 that Sweethome liked because it has the new rollers and bin so it picks up better and needs much less hair removal and other fiddling around.