I have used Manhattan Review
and they are 100% legit. I had already prepared quite a bit before going to the class and so I don't think it was a huge benefit, though the intructor & materials were excellent. It was more concerned with teaching the fundamentals than tricks or number picking strategies, which was what put me off Kaplan
The materials are aimed towards the higher end, I would say they are comparable to KAP 800, the Verbal is awesomely difficult.
I would certainly recommend it if you need a kick start to your prep, however if you are already quite advanced then it is possibly not worth it. But at the end of the day if it improves your score by 10 points and that 10 is the difference that gets you into your choice of school, then i'm sure most people would be happy to pay the $1k or whatever.