I'll go for underrated in regards to the market that it's in (not a typical destination, not talked about much) and the decor itself might not be everyone's taste -- therefore it'll be hit or miss for some. But The Hotel Kansas City is a beautiful hotel. I've enjoyed all of my stays there, and I'll go out of my way to be there anytime I'm in KC.
Admittedly, the other options for KC solidly in the "meh" category. But still. I've enjoyed this property more than any other I've been in throughout the midwest.