It does fancy stuff, but the fancy stuff it does consists of things that either alert you to something (and thus are over after a second), or that let you do some simple (and quickly done-with) interaction without having to pull out your phone.
Despite "smartwatch" sounding like "smartphone", there's really nothing you'd want to do with its UX that could last an hour.
Remember Windows SideShow[1]? It was a technology to allow OEMs to do things like putting an extra display on the lid of a laptop, that would indicate things when the laptop was closed and mostly asleep. That's what the watch is for: indicating things when your phone is closed and mostly asleep. If it indicates something interesting, you don't continue interacting with it; you take out your phone.
I'm not saying this to defend Apple's product in particular; it's probably far too expensive to get the right adoption in its market, and is more like an initial market-testing experiment in the same way Google Glass was.
But passive/reactive UX is a great idea, generally. The constant complaints about being stuck in a cubicle staring at a screen, or teenagers staring at their phones all day, are precisely because that's where our alerts are, and we don't want to miss them... but it's also where a bunch of engaging+distracting stuff is, so in the process of trying to stay on top of our alerts, we get constantly pulled back into engaging with the engaging stuff.
Imagine if, to check your email, you had to log into World of Warcraft or Second Life and wander over to your virtual mailbox on your virtual driveway. Lots of potential for distraction during that, right? But waking up your phone or your laptop, with its manifold social apps and games and media to consume, is nearly as bad.
Technologies with passive or reactive UXes allow us to treat technology as something poking its head into your door and asking a question, rather than something you need to "submerge into" like some sort of virtual reality.
I look forward to the day when every $5 Swatch watch gives you your phone's alerts. At that point, the glowing rectangle will become only a productivity device: something for creation, live collaboration, or media consumption; something you intentionally engage with for defined periods. But not something you need to context-switch back to every three minutes to see if you got an email, and end up reading HN while you've got it open.
[1] http://en.wikipedia.org/wiki/Windows_SideShow