Not long ago I purchased the Neato D80. The price point and positive reviews (even on Consumer Reports) led me to believe it could do a good job. Unfortunately, the D80 it gets stuck on fringe rugs, couches, chair legs. Once unleashed, it beeps for help several times a minute, literally. Unless you have a bare room with absolutely nothing in it, I don't see this machine being worthwhile. The suction is good, but that was beside the point with all the supervision it requires.
A few months ago I purchased the Roomba 860 as a replacement for the Neato (which has been relegated to the basement).
The 860 appears to be on par with the 650 for pickup power. It is quieter and more purposeful than the 650, which gives the appearance of bumbling around. However, there is one major design flaw with the 860 that the 650 does NOT have. The waste bin is extremely troublesome on the 860, because it has a very small hole for the dirt bin. This causes it to constantly show the "empty bin" icon, because pet hair will get stuck in the hole. It also makes it a dirtier process to empty, because I have to pick the dust bunnies out of the little hole in the body of the robot, rather than just upending the bin.
The 860 is more expensive than the 650, and due to this flaw I don't feel it's a worthwhile investment. The trusty old 650 is doing well after years of use, and even the occasional toddler riding around on it. It is the tank of Roombas. For ease-of-use, I recommend the 650 over the 860.