I recently started learning Common Lisp, and it’s been mostly great, but my two complaints are 1) memory usage and 2) deployment (copy source or distribute a relatively huge world image—and I haven’t found any way to get a fully static build without patches, even with ECL).
Janet could solve both of those, although I’d pay a performance penalty due to it being interpreted, and I assume there are a lot fewer libraries/tools. I really like the idea of a Lua-sized Lisp, but I’m not sure if I should jump ship from a traditional Lisp yet.