Other than it doesn’t always work…
A problem I’ve found that you don’t get with a messenger like ICQ or Yahoo, is that people add you and there’s no where for them to say where they got your ID from. You either have to figure it out for yourself by their email address or talk to them and ask… Which is fair enough you might say, but it would be a hell of a lot easier if you could have a “add me message” when you’re adding a contact so the other person isn’t left in any doubt.
It would just be nice to know if people that add you found your email address from a forum profile, a blog, a website, your MSN profile or randomly typed in a hotmail address… Wouldn’t it?