Yeah, I agree. Lua is actually my favorite language ahead of Ruby. I have F3 mapped in Vim to run my tests; one of my projects is an implementation of Haml in Lua, and even that runs all of its tests in a small fraction of a second. The more you work with Lua the harder it can be to go back to Ruby sometimes.
I like Lua, but it does lack Ruby's elegance and expressiveness. Its best trait may be that it's simple, and therefore performant.
On my list of gripes: Lua's attempt at OO, being implemented as hash tables, is even more pitiful than JavaScript's. Also, arrays are implemented as hashes (just like PHP!), which is just one notch below JavaScript again. I also wish for a more expressive regex syntax, but then that's the text processing talking.
