>huge library
>strong franchises (Ratchet & Clank, Jak & Faster, Sly Cooper, Final Fantasy, NFS, Burnout, GTA, Medal of Honor etc)
>most games had good campaigns but also allowed 2-4 player split screen campaigns or multiplayer
>jump into 3d graphics
>could also play DVDs

I've still got my PS2 plugged in for DVDs and nostalgia gaming