It's quite fast and it seems to scale well to large (though not necessarily to ridiculously large) repositories. The largest one I've used it with had a 1TB head revision - I don't know how large the history was - and a zillion files. Performance was still fine. (This is probably its main advantage, really: you can just put all your files in it. Then it's easy for everybody to get them, and you didn't have to think too hard about it.)

It uses the check in/check out model, so there's no problem with unmergeable binary files. There are per-user access permissions. Branches are folder copies. There's a GUI tool, but you can do everything from the command line as well (I believe that is exactly how the GUI tool does everything).

(UX is a bit hit or miss though. There's no git-style index, and the command line tool's output isn't as convenient to parse as you might like. On the other hand the diff/merge tool is alright and the UI for keeping your branches in sync is fine.)

I've never minded using it.