Despite the crowds this is a place worth going to, especially with kids. Make sure that if you do go that you book on the internet and can then go in the 'quick'(?) queue. In the school holidays this will still take you a while to get in, but is still worth spending the extra pounds.
Inside is dark, dismal and smelly. Just how you want it to be. There are lots of side shows with actors dressed up in the part. I was particularly thrilled in the 'Jack The Ripper' area to be accused by a prostitute of spending a tuppence on her the previous night! My wife didn't seem to be too concerned.
Particularly enjoyable were the court scene, the Sweeny Todd chairs and the Gallows ride.
It is great for the kids as long as they are not of a nervous disposition, and I would suggest age seven or older. My seven year old was fine, but then with three older brothers he is used to being scared! The only disappointment for him was that he was too short to go on The Gallows ride.
Definitely worth a family visit