The dragon is quite cool. If I was a little more patient, I would have waited for the new Castle set in August, but it was more or less worth $30 to me.
I'm thinking the general Hobbit hype now contributes to making the dragon valuable, but I'm expecting a huge Smaug to be released eventually. They can't not do that, it's THE iconic scene, moreso than even the balrog. However, considering the ridiculous security, I'm thinking Lego won't have the set this year even if the majority of the Smaug action is in this movie. Weta doesn't want merchandise to spoil their design - again. If Richard Armitage and Ian McKellen don't know what Smaug looks like yet, I doubt anyone at Lego does either.
The treasure chamber in general will be interesting. I'm guessing Smaug will come with some generic mountains of gold/treasure chests/props, that there will be a small Bilbo + Arkenstone set with more gold, and probably an armoury set with a few updated dwarves and loads of weapons.
That's the Erebor sets I see coming, anyway. Unless they invent something new, there's not a lot around the mountain that makes for interesting toys.