It's awesome. Way better than my old Roomba in my opinion. It's cleaned my entire house (I live in a fairly small, single-story house) 3 times now without requiring any intervention at all. I watched it the first day I ran it, and it does a fairly smart job at recognizing rooms. The only thing it didn't treat as a separate room was my main hallway, but it covered it completely as it cleaned the other rooms. The best thing is the only real maintenance required is to empty the dust bin and clean out the filter. The Roomba brush always got hair and other debris twisted up inside of it and it was always a pain cleaning that out every time you ran it. After 3 passes through my house, the XV-11 brush is still completely clean.
I've got it set on a schedule to run while I'm at work, and I've been coming home every day and it's found its way back to its charging dock every time so far. That's probably the best indication of how good its mapping system is. When it finished up the first time I ran it, it shut off the vacuum, drove out of my bedroom, into my kitchen, and back to its dock without bumping into anything and basically taking the shortest possible path back to the dock.
It has a couple shortcomings compared to the Roomba, but they're fairly minor (at least in my house, might be more major depending on your house/furniture). The main thing is that the laser range finder makes it treat anything it sees at about 4" off the ground as a wall. So if you have for example a skirt on your bed that hangs down low, it will see that and it won't even go under the bed. This actually works out well for me because I have a couch with a little skirt that the Roomba would always try to go under and end up getting stuck under, but the XV-11 doesn't even try. Another drawback is that the XV-11 is a tiny bit taller than the Roomba, so some things it won't fit under that the Roomba will.