It's a great language. Back in '06 I built a kiosk software platform on Lua. Hilariously enough I also built a REST based document store in Haskell, and we started using it probably three weeks before CouchDB came out. Weird languages are great if you're working in a field where you'll have to build everything from scratch anyway.

I wouldn't build a webapp in either of them, probably even today. The ecosystems for other languages are just too rich.