I went through the boot camp at Ambilogic last Dec.
It was 10 days of pure hell, but honestly it was worth it. I have been deploying Windows servers for about 10 years now, so I kind of had an edge going into it. I also had already passed 70-290 prior to going through the bootcamp.
They have something like a 98% passing rate. I'd say 75% leave having passed all the tests, and those who don't pass, pass the remaining tests on their own without any problem.
The good : You will learn something there, contrary to what people will tell you. They won't dwell on the stuff you don't need to know for the tests. You learn just enough to pass.
The bad : You learn just enough to pass. A typical day : Wake up at 5:30AM, study. Go to class at 8AM - 4PM. We usually brought dinner back and then studied from 6PM until 1AM. Go to sleep. Some days were easier, but most were a pain in the ass.
Ambilogic has my vote. They are very good people, and North Conway, NH is a nice little town to visit.