I honestly think Ninty is rated just right. In the console market, they have pretty much been doing their own thing as far as hardware and accessories go, so they pretty much consciously decided against appealing to those who want top notch hardware, and no gimmicks, opting instead for the cult system route, appealing primarily to nostalgics. They seem to be dangerously close to traveling down the same road as MS(who I think is the most overrated of the big 3), who pump out rehashes of the same games over and over again to appeal to their core fanbase, while pushing their gimmicks, despite regular controls working just fine. At this point, I think Zelda, and even Mario still have a reasonable amount of effort put into them, and Ninty does have a few other ips up their sleeve, even though they often don't spend as much time advertising or pushing those other ips, at least in the console market. I really hope Ninty doesn't turn into MS, because I still have a personal fondness for them, despite their choices regarding their consoles.
As far as the handheld market goes though, Ninty has, and always will be the king IMHO. The dual screen design, and the addition of a touch screen has actually managed to enhance my experience with the ds and 3ds, and Ninty's handhelds have always had way more going for them than just Mario and Zelda. I'm fond of the vita too, but the 3ds definitely has the edge in terms of exclusives. The 3ds isn't what I would call an underrated device, since it has done reasonably well. I think Ninty has just made better choices with their handhelds than with their consoles, and it has shown in terms of popularity. Any disdain or disregard Ninty has earned regarding the wii u, I think they brought it on themselves. They may not have been entirely wrong, mind you. They have in fact, managed to draw in plenty of longtime Ninty fans like moths to a flame, but that form of hypnosis clearly only works on their biggest fans.