Two squirrels are better than one!
I think we all groaned, just a little, when we heard that New Super Mario Bros. U and New Super Mario Bros. 2 would be releasing pretty close to each other, and hey, didn't we just get finished with New Super Mario Bros. Wii? Lord knows that's what I thought, but after sinking some time into this Wii U entry in the series, I'm happy to say it brings a lot of interesting new content to the table. It might be the best NSMB game yet.
Playing with the Wii Remote felt great, of course, and differed little from New Super Bros. Wii. The best new addition is the Squirrel Suit, maybe more appropriately called the Flying Squirrel Suit, which is this game's answer to the old Super Cape: you hold down the 1 button in the air to glide slowly toward the ground, and a quick shake of the Remote makes Mario take a quick vertical uptick, at which point he unstoppably floats downward, a bit like his descent with the Helicopter Hat (from NSMBWii). The Squirrel Suit really opens up exploration options in the air, and I found a wealth of coins skyward of the main stage thanks to it.

The other addition I tried, the baby Yoshi, is held in front of Mario just like the baby Yoshis in Super Mario World's Special World. While they will eat any enemy they come across, they never grew into an adult Yoshi. However, jumping across a gap and shaking the Wii Remote caused the baby to balloon up to a comical size—this allowed Mario to float across gaps. If left by his lonesome, the baby Yoshi will toddle off on his own and, inevitably, off a cliff to his doom, so it's good to keep him around as long as you can!
The thing that really impressed me though, more than the Squirrel Suit or the inflatable baby Yoshi, is the fact that the level design seems far more deliberate this time around. Stages are bursting with hidden passages and alternate routes, though the prizes don't usually amount to much beyond a 1-Up or a Star Coin. I'm sure that, like in NSMBWii, some of these hidden paths will lead you to alternate map routes.

Unfortunately, the fellow playing with me (on the GamePad) didn't have much to do. I'm a Mario veteran and I'm fully capable of getting through these stages without assistance. The few times my accidental colleague tried placing some "boost blocks" on my route, they screwed me up more than anything else. One poorly-timed block placement resulted in me losing my Squirrel Suit. The GamePad player also has the ability to tap—and stun—enemies, but this is, again, something of a useless feature when playing with an experienced platforming player. Now, the tables were turned when we switched controllers. Clearly a newbie to the Mario experience, my partner often asked for me to place boost blocks in specific locations so he wouldn't have to deal with a pit full of Piranha Plants or so he could get to the top of the end flag. I can certainly see the appeal of Boost Mode given a Mario player's potential inexperience, but Rayman Legends does this same thing much better.
I was surprised how much I liked New Super Mario Bros. U, and I'll be excited to play it when it releases.