The RL850 is my 2nd robomow, having owned the RL800 the previous 2 years. With several qualifiers, I have been most satisfied. Starting up; Others had reported that they recieved too few pegs. One bag was just enough for my 3,750 back and 1,000 front sq ft yard. Then I needed to add just a few more and discovered that I had not opened the 2nd bag, plenty of stakes. Just pull the perimeter wire taught at the corners then peg every 10', add a few more for the uneven spots. 1st thing I did was to put duct tape over its annoying little 1.5" speaker to muffle its shrill warnings. Yes, the yard needs to be smooth and have hard barriers around trees, planters, ect... For trees, it can ride up the roots with the rubber bumber sensor not getting compressed. With its 3 wheels, significant uneveness will show up in its cutting the grass. My yard has gentle mounds, some slopes, and the robomow handles those well. It doesn't seem to like numerous objects to cut around. For completely mowed grass in the intense July growing season, its best to start off in my yard by aiming it behind an area fronted by a planter and a tree. Otherwise, it doesn't get behind them as often and leaves a few unmowed patches. It follows the wire well yet there's a little lag before reacting, it isn't precise. I have a patio support pole 3" from the edge. Though the perimeter wire is properly located, robomow hits a slanted water meter box 4' beforehand. It veers 3" left, overcorrects back to the right and sometimes makes contact with the patio pole. Not a great problem, yet on those times, it corrects by swinging out for 6' leaving a swath unedged. Most all the lawn gets mowed except a small amount around the planter/trees. I do a little touching up when manually driving robomow back to its patio spot. The springy coil wire for the manual controller slides right into it storage slot. If you try to place the coil in there in a manner you think will work, it won't. Just hold the controller above the slot and lower, easy. Don't leave robomow working around neighborhood kids. It's probably not strong enough if anyone attempts to stand on it a second and its cutting blades are dangerous. One would have to work at it to get your hands to where the blades are, but idiots do exist on our planet. Low cut blades (you have to search and special order these) increase its effiecientcy yet can hit less than perfectly adjusted springler heads and you give up a margin of safety. My cats looked like they would eventually try to buddy up to robomow. So I would clap anytime they were within 5'. He now keeps his distance. I can leave home with it in my enclosed backyard but I wouldn't do so with it in the front yard, exposed to the public. It's quiet enough to use at 7am or 9pm, maybe in the middle of the night, if your neighbors house is 50' off and has double pane windows. It doesn't save much time but a lot of work. I used to mow once a week, now I roll out robomow