I have a DS lite from 2008 that still holds a decent charge (about 2-3hrs of battery life per charge) and works without issue. I don't know what Nintendo did but they did it well
Generally speaking Nintendo products LAST no argument there. The only thing that usually fails on their handhelds is the hinges...which happened to me twice on the 3DS before the 2DS came out. However never once happened to me on the DS.
Oh yea, the left hinge on my DS Lite has been broken for a few years. But honestly, I don't use my DS as an alarm clock (I tried, it wasn't loud enough
)) so it doesn't bother me much