I’ve used a reel mower for four years now. Funnily enough, before I bought that mower, I also posed the same question to the SDMB.
Its takes about the same muscle power as pushing a non self-propelled push mower. However, it cuts a narrower swath, so you’ll walk more. My back yard is about 50 feet long and 40 feet wide and I can mow it in about 45 minutes. Its a decent workout. I have to take a couple of breathers on a really warm day, but nothing I can’t handle. It keeps me skinny.
Pros
Cheap: I bought my mower at the Home Depot for $35.
Easy to Maintain: It takes me around 60 minutes once a year to keep the blades sharp. Its about a third of the size of a regular push mower, so it doesn’t take up much room in the garage.
Quiet
No exhaust
Safe: I mow in my bare feet, which I would never do with a rotary blade mower. I know its possible to cut your feet on a reel mower, but I’d have to do some acrobatics to even get a graze on my big toe.
Apparently the reel “scissor action” is better for the grass than a rotary blade.
Cons
It doesn’t cut as much height off the grass as a rotary blade mower, so you have to mow more often…I have to mow about twice as often.
If the grass gets too high, it won’t cut properly. The grass will lay down in front of the reel and not feed into the blades.
Even very small twigs will not cut properly in the reel, and will jam it up. A quick shake of the mower usually gets rid of the article, and you can continue.
If there are any bare patches at all, I’ve noticed the grass tends to grow sideways there, and not up. With a rotary blade mower, the blades act as a fan to suck the grass up before it cuts it. You don’t get this with a reel mower. So your bare patches can get bigger and bigger because the grass is growing long over that ground and inhibiting any little grasslings from growing up big and strong. That’s my theory anyway.
A reel mower doesn’t chop the grass into little bits like a rotary blade. I can get a bit of a thatch problem if I don’t rake it up every so often, which is a lot of work. I haven’t found a decent grass catching assembly for a reel mower. My fix for this is to make use of a friend’s rotary blade mower about twice a year to pick up all the thatch and throw it in my compost heap.
All in all, I like my reel mower. If you’re not afraid of a little work it can be a fine yard tool. Then again, I enjoy mowing the lawn, but despise going to the gas station. And I have a hard enough time keeping the oil changed on the toyota to worry about a lawn mower as well.
Good luck with your decision!