I wouldnt say that the Wii U is "Underrated" but "Low Rated".
From a Hardware standpoint is very lacking.
According to CNET:
The Good An included tablet-style GamePad can play games when the TV is in use; Nintendo has a core library of awesome exclusive titles; works with older Wii games and accessories; very kid-friendly. Access to a vault of your childhood classics. Off-TV play is great.
The Bad Can't play DVDs or Blu-rays; lacks a lot of third-party games available on Xbox or PlayStation; GamePad battery life too short; Wii U and 3DS handheld don't share games. On-board storage is severely lacking; Wii U interface is still way behind other consoles. Limited GamePad wireless range limits it to use barely one room away.
The Bottom Line The Wii U has shaken off some of its initial growing pains to become a superior kid and family console, with a limited but excellent lineup of exclusive games you won't find anywhere else.