Game Boy Advance SP backlit vs front-lit vs Micro
A comparison of the two different lighting technologies on the Game Boy Advance SP. The leftmost (purple) SP unit is the later AGS-101 model, with a backlight (like the Micro, DS Lite, DSi or 3DS). The rightmost (black) SP unit is the much more common older AGS-001 (front-lit) model. The smaller silver device is a Game Boy Micro (which is a Game Boy Advance in terms of the hardware platform).
All devices are on their highest brightness setting; the lowest brightness on the AGS-101 is substantially brighter than the highest brightness setting on the AGS-001. The Micro's highest brightness (shown; I believe it has five levels) is a bit brighter than the AGS-101's highest level, but I also find it a bit extreme and washed-out.
I love the chunkiness of the SP, and the shoulder-buttons are easier to press than those on the Micro. SP units can also play Game Boy cartridges from the original, Color and Advance eras (unlike the Micro, which plays only GB Advance carts). The larger screen is also a lot easier on my ageing eyes than the Micro. The only downside was the murky, poorly-lit screen - and the AGS-101 model fixes that problem completely.