We went to Universal's Halloween Horror night a few years back. I wouldn't recommend it for anyone less than teenagers. I spent the whole evening a bag of nerves. It was very dark, very misty and there were 'actors' jumping out at you at every turn. I didn't even brave one of the mazes - which look very scary - I did watch a video of one online and was glad I didn't go in.

DH thought it was great and anyone who is a bit less of a scaredy cat than me would enjoy it. He's going again this year with braver friends and I'm babysitting.
If you like being scared give it a go. On the positive side - nobody seemed to bother with the normal rides so I just did that instead with no queues.

MNNSHP is nothing like Universal. It's not at all scarey and great for kids. I'll be sticking with Disney.

You can buy MNNSHP online via the disney site. I just got mine through the post.