Good for small flat lawns as has been said above.

To cut long grass, you remove the front roller and replace it with a wheel on each side.

To sharpen it you put some valve grinding paste on the blades and push it backwards for a while. Don't forget to wash the paste off after though.

It won't work on wet grass.

Also, you might try an electric Flymo. Light and easy to push, just don't run over the cord.