They have some good info, but it's mixed in with some questionable stuff... and that's to be expected.
For someone who doens't know anything at all it may be a good place to start, though I think at times it overcomplicates things by trying to cover more than it should. They also allow for millions of options (i.e. who, in this day and age, will be dealing with Dolby Pro Logic or trying to create pseudo-surround out of 4 speakers and a potentiometer?)
I like their drawings, but I found their recommended loudspeaker placement to be quite a bit off from what we, THX, HAA, or ITU recommends.
That site sure is ad-heaven. It's like you pay an "ad tax" for every 200 words