Has anyone done this? What was your experience? Is it worth the $625?
I checked out the website, but it doesn't really provide much:
http://store.midohio.com/c-27-acura-high-performance-course.aspx
Most of the discussion on this topic seems related to cost and/or alternate approaches. Maybe this will address your actual question.
I took the course in 2002. It was my first time on a track anywhere and it was money well spent. I have been to numerous events since and the instructors, while knowledgeable and always helpful, did not have the intimate knowledge of the track that the Mid-OH instructors have.
HOWEVER, after five years of tracking my NSX, I think taking this course again would be a really great idea. The problem, if you have never been on a track before, is information overload. They are throwing so much really useful stuff at you that you miss a lot and much of it has no real context. With some experience you will get a lot more out of it. However, if you have picked up bad habits, you may have trouble unlearning them.
Now, when I first decided to do this, I weighed the pros and cons of paying the money for professional instruction and just attending HPDE events. The feedback I got was that HPDE instruction was too variable. Those who got good, knowledgeable instructors learned a lot. Those who didn't, didn't. And there was no way to really know at the time. You run the same risk at the Mid-OH school, but it isn't as great.
Learning to drive is a lot like learning to play golf. You can learn a lot on your own by reading and trial-and-error. You can get knowledgeable friends to teach you. You can hire a professional. Your odds are better (not certain, but better) with the professional.
BTW, I took my NSX to the school. It is a great track car but suffers a lot on some of the auto-cross-like exercises. OTOH, it is rear drive/mid-engine; the school cars are front drive Acuras and Hondas. If you plan to track your NSX, you are probably better off learning in it.