I bought the Earthwise 60120 on 25 Sept 2009. I have a corner lot which is about 10000 sq ft (< 1/4 acre); when I first purchased the mower it could just barely handle doing the entire yard. It was prone to bogging down where the grass was a little thicker, but I just raised it all the way (which is the one GREAT feature about this mower, the one lever to adjust all wheel heights) and mowed, lowered it back down to cutting height and went back over. Also, this mower is quite heavy (100lbs). Our yard is nearly flat, but it is a bit of a strain pushing it up our shallow slope; it would be quite tiring for even a slightly hilly yard. We mowed probably 10-15 times last season before the grass went dormant. We charged the battery regularly over the winter as recommended; but since we started mowing again this season, the battery life has steadily dwindled until now we only get about 20 minutes of mowing before the mower is too weak to cut grass. So, we have to mow 20 minutes, go take a 1 or 2 hour break, mow another 20 minutes, go take another 1 or 2 hour break, and then finish the yard. Preposterous! I just called the Earthwise 800 number and discovered that the battery only has a 90 day warranty! Obviously, they know the battery is a piece of junk that will probably not last a season. Since the battery costs over $100 to replace, a season's worth of gasoline (even at $3/gallon) would be a lot cheaper than replacing the battery every year. I was really hoping this would work out and I could leave gas mowers behind forever.