I have a lot of friends who went to NYU, Columbia and UCLA for law school and they all did testmasters (they all scored 99th percentile). They recommended it to me and I thought the course was solid. They have 17 lessons, 4 proctered diagnostics (plus 10-12 additional diagnosics online) and a whole host of supplemental questions online. I am sure most schools have this, but what I liked the most about testmasters was:
1) all their instructors must have scored in the 99% percentile. My instructor, Ian, really was an intelligent guy (on his first diagnostic he scored a 164 with no training....i know that pissed me off too!), I mean that guy never got anything wrong and was really good at explaining things. Plus he always made himself available for extra tutoring if needed.
2) In Toronto the class size is small because testmasters is new here, so you feel more comfortable in class and the instructor can really focus on specific issues that any one student may have.
3) They analyze every question to death, so you really understand why the answer is in fact the answer.
I didn't score as well as my friends did (87th percentile), but I was very happy with that, since I am applying as a mature student. When I started the course I scored in the 52nd percentile. Now that doesn't necessarily mean that my experience will happen for everyone, but everyone in our class definitely increased with time and instruction.
hope this long-winded answer helps!