The Jr. Olympics is in outstanding baseball tournament and will be one of the most memorable events of any boy's baseball playing days. It is also a fantastic opportunity for a very few who are chosen to tryout for the Youth National Team; and for those players their baseball prospects are greatly enhanced going forward. Keep in mind that out of approximately 1,500 age eligible players (this year it is players born after 1/1/90) only 36 are selected for the honor of trying out for the Youth National Team. From the few boys I know who've been chosen for the honor of trying out for the Youth or Junior National Teams, I've heard that the pride of wearing a jersey that says "USA" across the front is a feeling you just can't imagine until you've personally experienced it.
Now that I've said that, I'll also say that if the primary reason you're considering playing in the Jr. Olympics is for exposure, you're not focused where you should be. The JO's are an incredible baseball tournament that features many of the very best 16 year old players in the country and many of the best summer teams. This is a chance for many boys to compete at a higher level of competition than they've ever experienced before, with more pressure than before. It is a chance to find out how good they truly are, and to demonstrate it on the field in front of some people who can make a difference in their baseball future. USA Baseball does an incredible job of smoothly running two tournaments simultaneoulsy that feature approximately 1,000 games in a week. They are a fantastic crew and don't get all the credit they deserve for doing as great a job as they do.
In my opinion, if your son is asked to play he should consider it an honor and be thankful for the opportunity. Go for the competition, the exposure will take care of itself.