Last new feature added 16 years ago; Last fix (for 64-bit) done 11 years ago -- but likely, real development stopped a decade before that, when Arthur Whitney left MS.
What he did later was create K (and kdb+ and now shakti), which are significantly farther away from APL (of which A+ is mostly just a very opinionated dialect), but which I personally find overall cleaner and more consistent.
I literally just heard about K for the first time while listening to fast.ai founder Jeremy Howard talk about it in a podcast, less than 5 minutes ago.
You can evaluate the 32-bit version of q by downloading the binary from here: https://code.kx.com/v2/
The setup is a little annoying and you have to make sure q and the license file are in same directory or something, I vaguely remember that the error message was pretty cryptic but it is definitely worth taking it for a spin. It is an interesting piece of engineering and there are many interesting example scripts that you can find on the Web, although actually becoming productive in q is another matter entirely.
What he did later was create K (and kdb+ and now shakti), which are significantly farther away from APL (of which A+ is mostly just a very opinionated dialect), but which I personally find overall cleaner and more consistent.