I have lurked here for a couple of weeks and as my son is younger I found a lot of good stuff, but didn't really find anything I felt I could contribute until now. Passing on my experience in hopes someone can learn from it.
My son completed this program about six months ago with a local instructor. I must say he and I couldn't be happier with the results. For the last several years he has always played on some of our area's best travel teams, but it was certainly not because of his stick. He is an excellent defenseman and decent pitcher and that got him on these teams.
So as you can imagine being like most competitive dads I had many days of angst trying to help my otherwise very athletic son get over his inability to hit. His mother would argue it was my fault as I let him start hitting on non dominant side and did not make him switch to dominant side until this past year when almost twelve. Sadly she is probaly more right than wrong.

I spent lots of time and money on lessons (note word usage) trying to see some improvement. Always left these lessons feeling like we were making progress but now know I should have realized I was really just letting someone make a few bucks off me and my kid.
So May of 2010 ran across a local instructor teaching this method. The cost was outrageous but he and I were truly desperate. He was falling farther and farther behind and the grumblings were getting lounder and louder from his coaches. My guess he was at best a .200 hitter and zero power. My son wanted to try this program and we decided we would give it a shot.
After two professional instruction sessions (note word choice) I could see immediate results and a change. No live hitting yet but swing on video was starting to change. Long story short one month later hit first two homeruns in Cooperstown of all places and had a great fall season where he hit .400 and batting in the four and five hole by end of season.
So I should be a huge fan of Epstein system right? I think I am but more importantly and the reason for my post is that I think the most important investment as parents we can make in our boys' baseball futures is the commitment to professional instrucion. I think oftentimes we as parents get too hung up on what is being taught to our boys vs. who is doing the teaching.
There are lots of folks out there giving lessons. You need to find someone who is a professional instructor and who your son will click with as well. They will not only teach your son the right way but they will help instill confidence and trust which leads to more confidence. Hitting a baseball is a confidence thing. With it you can do great things, without it you have little chance.
Trial and error and if you can't see the results on the field then you need to move on, because when you find someone you can trust they can truly change things for your son. My son and I now believe in his ability and the confidence from that makes this so much more enjoyable.