Most of my consoles still work. That includes - among the older ones, anyway - an NES, an SNES, an N64, two GBAs, a handful of DS's (I've amalgamated collections since getting married), a PS1, two PS2s, a PSP, and a few Segas that I picked up at a yard sale. Can't remember which Sega systems they were, but I know they work.
I'm pretty sure I have a non-functional Gameboy Color sitting around somewhere and the N64 and NES were getting a bit spotty the last time I checked, but other than that everything's working well enough.