Lots already posted in this forum Search NTIS and you'll read plenty of history.
But in a nutshell, you'll find opinions from "best baseball experience ever" to "complete waste of money".
As long as you go in with eyes wide open and realize that most of the final rosters are predetermined, and your expectation doesn't go beyond playing at various tryouts and possibly Cary for the cost of admission, then you'll be fine.
As for college scouts, I've not heard of any scouts attending any of the regional events. Been several years since he was at NTIS in Cary, but even there, no scouts.