Never been there but-
Voted 11th Best Children's Museum in America by CHILD Magazine! Got 5 red stars when it came to parents reviews.
Open Tuesday-Saturday: 9:30am to 5pm and Sunday: Noon to 5pm.
My sister takes my nephew there all the time. He's 4 and he absolutely loves it. She tries to take him once a month or atleast every other because there's always so much to do and he has a wonderful time. I'd say it is worth the trip.
I've never been there, it looks like fun though. Here is another great place to take kids, its not quite as big as a museum but its a little closer than Richmond. http://playwisekids.com/There is another place similar to that one in Woodbridge VA but I cant find the website for it right now.