I've had a Vespin for nearly 2 years. WOrks fine. We have some algae that grows in the tank if you don't use it too often. It brushes right off. On my old toilet, you had to scrub it off. In general, no brown streaks either!
Note, some people are finatics, and use strong cleaners on everything (the Sanagloss has some natural properties that help in this area). You can't use them on the finish, you'll destroy the special properties. You can read about it on the www.totousa.com site. If you do a google search, I think you will find some reviews as well (Popular Science, if I remember correctly).
I've got a new vanity sink with that finish ready, soon, to install. I hope it works as well as the toilet.