Honestly, I like the idea of a hand-held, and there are some good games out there on them. But underrated? For me personally, they're overrated.
But, really... My phone just does it better. I guess I apply the same mantra I do to PC's, to phones. I want a "do everything" machine. Not a 3DS that couldn't even hold porn. I suspect the main reason why portable games get so little spotlight is because we don't have our faces in games literally every waking second we're in or out of the house.
Typically, when I'm out of the house, I just don't have time to do much more than half a game of "Ring Defense" or "Battle cats." I'd rather read up on what's important for work, check local news, or look up information for games I already own. To be, the absolute biggest problem with portable gaming is that the games I want to be portable, are PC only. And the games I do want to play portable on my phone, or otherwise, cannot be played the way I want. (Long War is not built for phones. There is no modding scene for MineCraft portable. (And the controls are atrocious.) Minecraft isn't available for 3DS.) I've emulated console games on my Tablet, and I've had a 3DS given to me for free. Both of which are collecting dust, and I'm hoping to maybe, just maybe turn a profit on that $20 tablet. Which is extremely unlikely. Both devices turned into an astronomical waste of effort and money. Maybe EB Games will give me $100 for my 3DS and games. But maybe they'll just fuck me instead.
I drive, I can't play games.
I work, I need to stay focused.
I do chores, can't put my shopping list on the 3DS.
I bike, why play games when I'm on the trail?
I party, how insulting is it when you're talking to someone, and they just pull out a vita or a phone?
When I was younger, I'd pine for one on the bus. But that's the only other time I'd have for gaming outside of my own home or LAN parties. If I'm home? I got a big machine with a very cozy chair with more, better games. Sure, the bed is cozier. But my bed is for sleeping. Sleep is something I need to be aware of.