It is very interesting reading the Tripadvisor reviews for Katmandu. Firstly, everyone mentions that it was empty. There are a lot of glowing reviews posted by people who have only ever posted 1 review, which always looks highly suspicious. The other reviews which can be taken more seriously all say that it was overpriced (they paid US$ 120 a head) and there wasn't a great deal to do there. Evidently 9 rides, and most are like 3d based experiences.
I do hope you go Nan as I'd like some honest feedback on whether its worth it, for US$ 49 a head. I think it's worth giving it a try reasonably soon as I get the impression it won't be around for much longer.