Also, do not forget an easy and powerful sandboxing that you can achieve with Lua by selectively including/excluding parts of its std library at compile time an

Also, do not forget an easy and powerful sandboxing that you can achieve with Lua by selectively including/excluding parts of its std library at compile time and running Lua itself in a thread with no (or minimal) shared state. This alone is priceless when embedding scripting into an application.