I moved to a new house with a large garden earlier this year and decided to invest in one of these. It has so far saved me many hours of monotonous grass cutting.
As a bonus the grass now looks much healthier, I guess as a result of the mulching/ feeding effect of the grass cuttings.
I have it on the 6hr a day program which is more than enough to keep the 400-500 sqm lawn neatly trimmed. I've only had it a couple of months but the battery life seems great.
It is very quiet and you could easily have it on at night without noticing any noise at all.
Considering this costs as much as a reasonably good self propelled lawn mower (and nothing against a ride on) it's incredibly good value. Not to mention the hours/ days of time saved.
Yes, you have to spend a few hours pegging out the boundary wire initially (most of which has now disappeared into the surface of the lawn) but it is well worth the time spent getting this correct. I only routed it around one of the big walnut trees I have as the large roots are exposed and I didn't want the blades hitting these. It bounces off the other, smaller trees and obstacles and carries on cutting fine. I've had no issues at all with blades cutting any of the wires as I've read in other reviews.
It copes well with slopes/ uneven ground. I have a garden path, which is the same level as the grass. It trundles over this easily without a problem and continues cutting the grass the other side. It managed fine, even though there were some walnuts and beech nut casings all over the lawn during the autumn. I set the blades at 35-40mm so they would miss these, which is still short enough to give a neat look to the lawn.
I have no reservation highly recommending this. If you are unsure (as I was), just try it. You won't regret it!