Welp, the cinematic is out now for your viewing pleasure, and the response is... mixed. While pretty much everyone praises the technical quality (Blizzard's got that cinematic magic, which makes it all the more surprising that they went with live action for the movie), there is some back and forth on whether this cinematic stands up to the other two. While fans of Arthas definitely got their fill (and it was interesting to hear Terenas' voice echoing from the past, which hearkens back to perhaps the best cutscene Blizzard's ever done), other players were disappointed to see that this cinematic doesn't follow the standard "various classes and races battle it out" formula. And that only shows that this expansion will be very much more about the guy in the Lich King suit than anything else.
We'd point out, too, that this trailer didn't really have a "You are Not Prepared"-style catchphrase (though the word "King" definitely echoes with significance right at the end there). Clearly, Blizzard chose to go a different direction this time around, and whether it worked or not, of course, is up to you.
Unfortunately, Gnomes didn't get their day... or did they? When players cry foul on the forums, Vaneras (in official blue text) answered with the picture above. Can you see the Death Knight Gnome hidden in among the Undead army? I like Schwick's answer even better, though -- there's probably a Gnome Rogue stealthed right behind Arthas. Those little buggers are everywhere.
Update: A few people are suggesting that there is more to the trailer that we haven't seen, but Nethaera has confirmed that that's everything. She commented on the forums that the trailer only showed half the battle, but later confirmed that she meant the story was incomplete (and that we needed to complete it by going to Northrend), and not that there was more of the trailer to show.