Which one do you think has a better chance of controlling the living room?
I think the
Wii U will win the functionality war but
SmartGlass will dominate the raw numbers. Reason being, SmartGlass is coming to Windows 8 PC/Phones, iOS and Android. There's already millions of mobile devices out there and (presumably) all someone has to do is download an app whereas the Wii U has to build its user base from scratch. And of course, more users equates to more devs supporting SmartGlass.
From a gaming standpoint the Wii U controller looks to have the edge based on the fact that it's actually a controller - i.e. analog sticks, buttons, etc. It's much easier to glance down at the screen on the controller you're using while playing a game instead of a screen on a separate device (if that makes sense)
The problem with Nintendo is and has always been (since the N64 days anyway) lack of third party support in games/apps, a refusal to really invest in a true quality online network, and a "kiddie" image that it has not been able to shed since the Gamecube. Sadly, I can see all three remaining consistent in the upcoming gen with the Wii U. The other issues Nintendo faces is the fact that the graphical capability of the Wii U isn't much different than the current HD twins and the majority of "killer apps" are games we played last year (Mass Effect 3, Batman Arkham City, etc) or ports of games coming to other systems (Assassin's Creed III). The one thing Nintendo really has going for it is exclusive games, the Mario's, Zelda's, and Kirby's.
The SmartGlass could be great for Microsoft as it lessens the requirement of usage; all you need is a tablet/smartphone which many of us already have. The problem I see here is that it's really up to content providers to make this thing a success. If Netflix, Hulu, ESPN, Disney, EA, Ubisoft, etc. decide that the tech isn't worth the time, you won't see rich content or extras as shown at the E3 presser. Why spend the extra time/dollars on making a game, app, or movie SmartGlass compatible when you may have to do it all over again in a year's time? While last year was the most successful for the Xbox brand in terms of sales/profit, it is clear that the Xbox 360 is on its last legs.
I can see a lot of these ideas being implemented in the next gen though which is exciting. I hope both succeed, but I'm not entirely sure they're fighting over the same space or audience. Nintendo has always marched to the beat of its own drum and I don't expect this to change.