I think it's very convenient. Just plug it in, wait a few minutes for it to heat up, and it's ready to go. Literally just have to put your meat on it, close it, and wait for it to be done. The cooking part on the more expensive ones are removable from the heating element so it's easier to clean, but even the cheaper ones (like the one I have) clean up really easily.
It's going to vary by how thick the meat is, but in general I think it cooks at least 2x faster than in a pan on the stove. It heats from both sides and less heat is loss to the surroundings because it closes on the meat. You also don't really have to watch it as closely to make sure it doesn't burn or splatter like in a pan.
Edit: I'm probably going to buy a new one next year so I can cook more at one time. The one I have now can only cook 2 normal sized burgers at one time.
This one looks nice.
