Here are the things you need to know.
You will not be prepared for how small it actually is. I’ve been looking at pictures for days and days, and I was still shocked when it arrived. The box looks as though it could not possibly contain it. It still manages to fit pretty well in my GBA case, though. I just arrange the games in the missing space.
The L/R butten placement - behind the screen, on each side of the base - that is going to take some getting used to. Right now that feels pretty weird.
It came fully charged. Thanks, Japan!
Comparing it to an Afterburner is more complex, not to mention highly subjective. For example: If you have installed the whole ball of wax - i.e., the “potentiometer” brightness dial thing - into your GameBoy, then you actually have a little more functionality than the SP, which only has “on” or “off” for the light. In virtually every other case, I need to give the edge to the GBA SP - I won’t waffle on the point or try to mitigate it. I prefer it.