The only issue, perhaps, with Legolas' presence is that it renders the casting of Evangeline Lilly as Tauriel more token than might otherwise be the case. Yes, it makes sense to add a reasonably canonical female character into this all-boys club, but if you're then going to pair her with Legolas (as a team, not in the sack; minds out of gutters, y'all) and make him better at everything, that slightly defeats the purpose. Her falling for Kili likewise seems unmotivated by anything save the notion, again, that Jackson simply wants his movie to have everything in it, including romance where none was before.
Then there's Smaug himself (Benedict Cumberbatch again), who only shows up at the end so it's best not to say too much about him. Except this: when Sherlock's dulcet tones emanate from a giant reptile, it leads me to imagine a hundred heinous fan fictions being written the moment certain eager fangirls (and some boys, perhaps) get home and online.
And with that all said, the real question: is it good?
On balance, yes. As a fragmentary middle piece of something, it isn't complete unto itself, which makes final judgment hard. With that in mind, it is very fun to look at, especially in 3D, which isn't being presented in 48 FPS this time, but it was shot that way, and is not just nicely clear but also features a few cheap tricks by Jackson that remind you occasionally of how it can be a fun gimmick to just throw shit at the audience. I know we're not "supposed" to enjoy movies that do that, but I always have.
That said, there are one or two cringeworthy moments that will most assuredly be harped on like Indiana Jones' nuclear fridge - that pointless final sequence I mentioned earlier has Thorin body-surfing a shield down a river of molten metal that heated from solid in record time. It is not one of the cinematic Tolkien-verse's finest hours.