It still uses the traditional 5-line staff notation, but sharps and flats are given by the shape of the notehead. The key signature is still there, but you don't need to remember it, or accidentals whilst playing. It's similiar enough to ordinary notation that you can pick it up in a few minutes and it's easy to switch between the two.
I'm a grade 8 + amateur piano player, but I've always been a very poor sight-reader and I found the notation really helpful. I get very frustrated with unfamiliar pieces because I keep forgetting the key signature and hitting wrong notes. But I can sit and sight-read pieces in simplified music notation for hours on end without making any mistakes, which makes it a lot more fun, obviously.
You can get instructions and scores from the website.