In my opinion, lua has a very unnecessary bad reputation. This is obviously because it is much easier to use (well, at least definitely much easier to start programming with it... i.e. download luaplayer, write scripts in text editor... no compiling), which leads to many more low-level programs being written in it. This is very understandable. However, it doesn't make much sense why people would generalize lua as being inferior to C/C++ only because of the simple/low-level/useless things being written in it. Lua does have its issues as a scripting language on the PSP, but it is also very capable. Many people don't give it enough credit. It is the people using the language who determine its capability, for the most part. I hope that people realize that lua is not as useless as many seem to think, and that just because it can be easy to program in, does not mean that it is not a powerful language.
Those are just some of the impressive PSP lua games.