I attended a NUS this year in OH. I am going to attend another in 2009, since it's in my state
if I only knew last year we were hosting one this year! Anyway, I agree with alot of the comments here.
The real answer is if you go with your head on straight you will learn something. I have never gone anywhere and not learned something, it might be what not to do, or just a refresher that yep you are doing xyz correctly.
The amount you will learn depends on your past. Have you attended other schools? Were they patterned after the NUS? Did you pay attention during those, and learn and incorporate the learnings in your umpiring?
My personal experience was ok with the school. BUT, I, like many others in other states, have an unfair advantage. We have had VERY good state schools, and a member of the NU Staff has been at the majority of the state schools that I have attended in my career. Our state schools have been the same drills same points of emphsis as the NUS. That was a sort of let down to me, in that I felt like I had driven all that way, spent $$ on clinic and hotel room etc. for what I could have gotten 15 miles away from my house! BUT now again having your mind on right is key, and knowing you can always learn something is important. I learned several things at that clinic, all "small" points but all worth my weekend trip and my $$. One small almost a joke comment from Kevin has helped me in my plate stance this past year, helped my knees a TON. Nothing I hadn't heard before, but reprased in a way that made a light come on for me and helped me do what I had been attempting to but had been feeling awkward till then. And BTW his comment was to someone else about their stance, not me....so my #1 take away was something that I overheard being said to someone else, so bottom line is pay attention and you WILL get your money out of the clinic, IMO!!
Also what others have said it is a great chance to be seen by the "powers" that be and to get to know them and them to know you, having a face with the name helps a lot and also if you can manage to do something right during the drills doesn't hurt either!
that must be my problem...