Overall the board as served me quite well, but there is almost always room for improvement.  Below are a few changes that would make if I get around to making another revision:

Add a jumper in series to the power LED.  When it comes to working with low-power projects and running it off of batteries,  the little bitty LED can consume quite a bit of power compared to everything else.  One could simply not solder in the LED, but this would be a more flexible solution.

Simply do a power plane for the top layer.  A thing that I've ran into when designing the board was having trouble fitting in nice thick power traces for everything.  It's perhaps a bit overkill, but why not?

Possibly squeeze in an LDR. I've found it quite useful on my 1284P board, might been worth trying to squeeze it in.