The Robomower RL850 is reasonably priced for a robotic mower. It mows automatically but has to be driven to its starting point with the included remote control, then returned to its charging station the same way. Like all Robomower models, it has excellent safety features. It does not include a rain sensor that stops it from mowing during rainstorms, but it is weatherproof. The included charging station is not, however, so it must be kept in a garage or other sheltered area. This is one of the few robotic lawn mowers that gets a good number of user reviews, so we have better objective data for this model than for others.
The Robomower RL 850 is reviewed by more than 60 users at Amazon.com; Epinions.com also offers owners' perspectives. The forums on Robomower.biz have advice and information about the Robomower RL 850.
Amazon.com publishes owner-written reviews and ratings of the robotic mowers sold here. The RL850 gets almost 30 reviews, many of which are highly detailed. Many owners love their Robomowers; a few complain that the RL850 broke down early and often, and quite a few complain about customer service.
Review: Friendly Robotics RoboMower 21-Inch Automatic Cordless Electric Lawn Mower #RL850, Contributors to Amazon.com
About 30 users post reviews of different models of Robomowers here; it gets an average rating of 3.5 out of 5. Some of the reviews are quite old, but some are as recent as 2009. Several owners review the RL850; most like it.
Review: Friendly Robotics Robomower, Contributors to Epinions.com
Two forums here concern Robomower models: Robomower Lawn Mower Talk and Robomower Help. Each has posts about the RL850, and both are worth checking out. The Robomower Help forum is a good place to troubleshoot any problems an owner might encounter, while the Robomower Talk forum gives owners' first-person perspectives on how the RL850 performs. One owner, for example, says his RL850 can handle slopes steeper than 15 degrees.
Review: LawnBott Robomower Robotic Lawn Mower Forums, Contributors to Robomower forums