I never really could get into handheld gaming, until I got into mobile (ironically). It takes me back to my early PC days when I would download dozens of shareware games and play them for 20 minutes at a time. Then every once in awhile you would play something amazing that you would sink dozens of hours into. There's little risk (in terms of dollars/time), so the rewards don't have to be so great.
But traditional handheld gaming always felt like a gimped experience. Like drinking a non-alcoholic beer or something. Rpgs, SRPGS, platformers, action, etc always felt like it was missing something, even though you were spending 30-40 dollars for it.