I haven’t watched it yet (and no doubt by the time I get around to it it’ll be long gone) but you the notes give you an idea of just how much fat there was in the trilogy:
The investigation of Dol Guldor has been completely excised, including the appearances of Radagast, Saruman and Galadriel. This was the most obvious cut, and the easiest to carry out (a testament to its irrelevance to the main narrative).
The Tauriel-Legolas-Kili love triangle has also been removed.
The Pale Orc subplot is vastly trimmed down. Azog is obviously still leading the attack on the Lonely Mountain at the end, but he does not appear in the film until after the company escapes the goblin tunnels (suggesting that the slaying of the Great Goblin is a factor in their vendetta, as it was in the novel).
Several of the Laketown scenes have been cut. However, I’ve still left quite a bit of this story-thread intact, since I felt it succeeded in getting the audience to care about the down-beaten fisherfolk and the struggles of Bard to protect them.
The prelude with old Bilbo is gone.
Several of the orc skirmishes have been cut.
Several of the action scenes have been tightened up, such as the barrel-ride, the fight between Smaug and the dwarves (no molten gold in this version), and the Battle of the Five Armies.
A lot of filler scenes have been cut as well. For example, the 4-minute scene where Bard buys some fish and the dwarves gather up his pay.
I have to say I didn’t mind the addition of Tauriel so much, the book has precisely female characters (and she was a bit of a badass), but if you’re going for purity she has to go (in which case I hope Legolas’s cameo has more to do with the necessity of a shot than fan-service).