I trained at ATP a couple of years ago. Overall, I enjoyed the program. Lots of flying and good experience. You pay exactley what is quoted. The powers that be at ATP are stand-up individuals. Unlike most flight schools out there.
However, (just my opinion) I found the training to be marginal. You are trained to pass the checkride. The examiners are NOT ATP staff and do NOT just give away the ratings like some people think. The instructors however do have gouges on the examiners and you are taught the checkride. At least this is the way it was at a couple of locations I took checkrides from. Most of the instructors at ATP are new instructors with very liittle time and virtually no flying experience outside of ATP's training pipeline. They get hired at the regionals within a few months of instructing because almost all of their time is multi time. I found the instructors know ATP procedures and aircraft very well, (as I did when I graduated) but very little else. If I had to do it all over again, I would still chose to go to ATP. There really is no better school out there if your goal is to get to a regional fast. Of all the different phases of the program, I felt the CFI training was severly lacking.