I got a George Foreman grill when I rented a place that had the grill inside the oven (darn silly idea to make ovens like that, if you ask me, since it means the oven can't be used at the same time). Anyway, as Pique said, it can dry out some meats (particularly chicken and steak), but I find it ideal for sausages and rashers. It's also great for making paninis, or toasted sandwiches with large slices of bread that don't fit in a standard sandwich toaster. The 'melt' feature wasn't available when I got mine, but I would definitely have opted for that if given the choice.
The newer models come with detachable plates, which would be worth considering. That being said, it doesn't take much to clean the ones with fixed plates - just wipe the plates with hot, soapy water while the grill is warm.