I've never played an SP2, but I love my SP1.
I was playing Final Fantasy Tactics on it just this afternoon! And some Mario Kart yesterday. And some F-Zero the day before that... :oops:
Few consoles, handheld or otherwise, have gotten as much use as my GBA SP, which I've owned since about the time it was released. It is up there with my TG-16 and SNES.
I am very tempted to hunt down an SP2, but I'd have a hard time letting go of my SP1 just because of all the time I've spent using it over the past decade (or so).