As a member of the first group of students to take the new SAT, I'd have to say the results have, overall, been postive. Yes, there is now an essay question on the test, but the SAT II writing section (which used to be required for most colleges) already involved an essay, so, in reality the change isn't too big. I took an SAT preparation class the summer before I took the SAT and found it useful, taking a few practice SATs before the actual test date made me a lot more comfortable (at least with the format, if nothing else).

I also took the newer SAT and found the essay portion of the SAT I to be rather limiting. When I took an SAT class, they told us to just think of two famous people like Martin Luther King and write a five paragraph essay using them regardless of the topic. Overall, the SAT prep courses just emphasize shortcuts and tricks rather than accruing a body of knowledge that is relevant to furthering one's education.

I taught SAT prep courses for four years, with several different companies.  I do think that coaching can be very effective -- most of the students in the programs I taught for had score improvements, some of them significant or even incredible gains!  However, it is true that preparing for the SAT doesn't really teach you anything beyond how to take that one test, and some esoteric words (esoteric, in fact, was on their vocabulary lists).  

One thing that really bothered me about teaching for SAT prep companies was that like most educational opportunities beyond public schooling, prep classes cost a lot of money and are advantageous only for people who can afford it.  I'd love to see more non-profits tackling this gap, because it's just not right that some students' scores reflect family income more than ability and effort.  But that's another topic...

There a ton of great websites out there.  When I was studying for my GRE I used the number2.com  It is a free website that helped me a ton.  Good Luck!