I covered this before in part but I'm not really a fan of third party URL shortener type services.

It's hard for a user to know where any particular link goes.

There *is* a way for a computer to dereference the link to figure out where it goes (I'm not sure if this makes requests or not to the server after a link service's server, I haven't looked into the technical details of it, I know such tools exist though), but a user would not only have to know about that tool, they would also have to manually put the URL into the tool to figure out where the link goes. That's not very user friendly.

Also, links appear to drift over time. One possible cause of this is the link expiring. That can theoretically be a security risk where a user encounters an old link and it points somewhere unexpected. Even without that case though, it's not a good experience for users.

A short URL also doesn't really add value. I have never seen a situation where someone has a shortened URL and I think "gee, this short URL is a great idea, I always have a bit of irritation as I can't immediately figure out where on earth the thing goes.

These things might also constitute a #privacy risk...