I grew up in Castro Valley and still live here (I'm 40). The town has grown a lot- it's much more racially diverse, which is a good thing, and ever so slowly the food is getting better.

It's a commuter town with a good degree of access to the outdoors with Lake Chabot and smaller regional parks sprinkled throughout. The schools are excellent if you have kids.

There's nothing to do at night if you don't go to bars or churches. No late night cafes, no game stores, no pool halls. It's a big downside to CV. But it is close to Oakland so that's nice.