It's written in broken English, and many external urls don't work as well, but it probably contains some useful material. The author himself doesn't recommend it to beginners though:
"I assumed you have high school mathematics background (i.e. basic trigonometry, Euclidean geometry, etc)."
I'm also fond of this quote he included:
"It's like if you want to be a good pianist, you have to do a lot of scales and a lot of practice, and a lot of that is kind of boring, it's work. But you need to do that before you can really be very expressive and really play beautiful music. You have to go through that phase of practice and drill." —Terry Tao
"If teaching is reduced to mere data transmission, if there is no sharing of excitement and wonder, if teachers themselves are passive recipients of information and not creators of new ideas, what hope is there for their students?" —Paul Lockhart