Yes, Lua 5.1 was a very good version. Lua 5.2 made some significant changes in how global variables work, which lead to a split between Lua and LuaJIT [1][2].

Yes, Lua 5.1 was a very good version. Lua 5.2 made some significant changes in how global variables work, which lead to a split between Lua and LuaJIT [1][2]. Lua 5.3, with true integer support [3] and some UTF-8 support made for a compelling reason to update. Lua 5.4 is out now with support for a more deterministic way to release resources. I think LuaJIT being mostly stuck with Lua 5.1 is a cause for the lack up uptake on more modern versions of Lua. [1] Mike Pall, creator of LuaJIT, disagreed with the direction that Lua 5.2 went and remained with Lua 5.1 semantics. [2] I personally found Lua 5.2 a "meh" version and didn't bother upgrading. [3] Including some functions to pack and unpack integers and floats into strings, in both big-endian and little-endian formats.