My son first starting going at age 13 and attended 2 of their boot camps, 2 of their advanced camps and spent a month at the ranch doing the summer program as a 16 yr old. It's a great program and you will learn a lot about proper mechanics for you (not a cookie cutter program). You will be given some drills to work on based on their assessment of your areas of improvement. I know the program has changed a lot since my son went through it and the prices are much higher now as well.
My son did both TBR and then moved on to Driveline and both helped him greatly and he is now pitching in college at a mid-major D1 program. However, there are no secret formulas that you will get from either program. You will get out of it what you put into it meaning the key is a lot of dedication and hard work. And it's not a linear type of improvement. You will see your velo increase then plateau and maybe even decrease, but the key is to stay totally committed and work through those peaks and valleys.
I believe both TBR and Driveline were invaluable experiences for my son and helped in his development. But he had to do the work in order for it to pay off, which he did.
The hard truth is that most kids who go through these programs don't apply that total commitment and it ends up being a waste of money, but if you put the time in then I would enthusiastically endorse both TBR and Driveline.