Debian Stable can be made as nice as any other Linux desktop OS. It takes a little work getting a Debian Stable setup with codecs and flash and some polish to make it look good on a desktop. But once done, you won't have to worry about updates breaking it or creating bugs. I have never once regretted using Debian Stable, in fact I'm using it right now
Mint will never do it, but if they offered a Debian Stable version with updated Firefox and Thunderbird and put some Mint polish and codecs on it, there would be little complaining about the finished product IMO But it won't happen.