Nightmare on the Bayou is all right, but not really worth $30. The $30 includes the two main houses plus two trailers afterwards.
The first main house is mostly outdoors, with the standard sort of chainsaws and lunatics. There were a few scary moments, but that part was rather disappointing overall.
The opening of the first house requires extreme bending over to get through, so anyone with back problems may want to avoid it. Also there's a lot of mist. It was the wet variety, which left us a bit damp. It might be a good idea to put electronic items in plastic bags, and if you're wearing glasses, don't expect to be able to see well.
The second part is 3D. You're given glasses before going in. This part is much more exciting than the first. The 3D effects were a lot of fun, and it was incredible visually. This one was also more scary.
The two trailers are really quick to go through, and felt kind of unnecessary. The second trailer could be difficult for anyone who has problems with claustrophobia.
I'd heard parking was an issue, but we went early so had no problems. There really aren't a lot of parking spaces around there at all, so they wouldn't be able to handle the kind of crowds that show up for Phobia or Screamworld.
Overall I'm glad I went. This was the only haunted house in Houston I hadn't been to before, so it was interesting to see, but I still feel like it's not as good as Phobia, and maybe around the same level as Screamworld.