Let me start by saying I really love Cooperstown, the town. It's an awesome place. Double day café - awesome. Shops - awesome. HOF - awesome. The fact that there isn't a whole lot to do - awesome (although fishing, boating, golf, etc. are all there). I certainly could spend several weeks there over a summer kicking back and relaxing from this daily grind.
Now, as for Dreams Park, consider me neutral. If you have the opportunity to go, then go. But you're life will not be destroyed if you don't. It's actually a summer camp for baseball. Drop kids off, pick them up in a week. Kids love it. I didn't much care for the short fences and the spectator areas. I don't much care for the gestapo like mentality that if you have the wrong belt on you're banned for the week. The staff does a good job getting games in -- we saw a lot of rain, but got 4 or 5 pool games played (yes, even at 1:00 am). Scheduling kind of sucks in that there is downtime between games, so you can't really do a lot before it's time to get back to the park (I'd rather play back to back and have the rest of the day off).
Now I will say this. If you go with a good group of families, the experience can be so much better. Our team wasn't really that way. We had factions. Nobody truly was friends - we don't talk/see to any of the parents after several years. There is too much time and closeness not to be with people you like. You can't go watch from the outfield - you have to sit right next to that crazy mom. And if your coach is a tool, watch out. Like anything, I guess good people make the trip all that much more enjoyable.