Works exactly as advertised, check out the Stan's website and watch the videos! Follow the instructions carefully and don't get in a hurry.
I can run as low as 30psi for massive traction, and not a single flat. Not a single burp. One small problem - they will leak down slowly, after a month (January) of sitting, they lost air down to under 20psi, but I always check air before every ride anyway.
I've helped 5 others install Stans, only one we couldn't get to work - one well used Kenda just wouldn't seal at the rim, replaced that tire and problem went away.
Even at the same pressure, you can feel a more supple ride and less rolling resistance.
Saved about half a pound off my bike!
Don't forget to add more sealant every six months or so, not sure if it dries up or gets "used up" but it slowly vanishes - just shake the wheel and listen for splashing sounds