Man, deciphering that is painful.
Spoiler warning for those who haven't seen the movie
The thing about the action sequences and the battle, is that that's pretty much how it happens in the book. There are a lot of Peter Jackson-isms, but a battle split between 5 armies isn't going to be a snooze fest, no matter how you spin it. I've seen discussions about the books that are somewhat split on who the 5 armies are. Some say humans, dwarves, elves, orcs, and wargs(this is based on the phrasing in the actual book), while others say humans, dwarves, elves, orcs, and eagles(which is suggested by people who view the eagles as a race capable of entering war, whereas wargs are just beasts of war). I believe the second option more. The way the movie is framed, the 5 armies are humans, elves and dwarves, with two armies of orcs(Dol Guldur led by Azog and Gundabad led by Bolg). But then the eagles come swooping in out of nowhere, Radaghast is all jolly n shit. And wargs are kind of mentioned off-the-cuff at one point. Like, just priming the audience and introducing the armies is like, half of the movie. It's ridiculous. But that's kind of how it is in the books. "Oh yeah, the elves are here. And now more dwarves! And the orcs n shit!(paraphrasing JRR Tolkien, of course).
On top of all the excitement, the love between Keeley and Turiel is made up by Jackson - Turiel is made up entirely, Legolas has no part in The Hobbit, and Azog is made up by Jackson - as is the struggle between Azog and Thorin. I'm not 100% sure, but I think the worms are bullshit made up by the flood of video games and used by Jackson. I don't remember them in the book, but I read the book a long time ago. Perhaps they exist in the Silmarillion but I haven't read that either. I'm fairly certain the Dol Guldur stuff is made up as well. In the book, Gandalf is off investigating a necromancer(who we know is Sauron, even from the books) and it's never really stated what he was doing, so pretty much everything about that story arc is made up(I could be wrong). I also don't recall trolls of any kind in the orc army. Trolls are turned to stone by sunlight and the battle happens during the day. This battle happened far before Mordor was capable of spewing ash into the sky to shield his army from the sun, and the trolls that can operate in sunlight (called Olog Hai) were bred for the same reason Saruman bred Uruk Hai(so they can fight in the sun), though I don't know if they existed at the time of the Hobbit.
In short, it doesn't take essays(ok, that was wordier than I thought it would be), but it's well understood that The Lord of the Rings and The Hobbit both suffer from Peter Jackson's Reality Distortion Field. It actually kind of irritates me that the post suggests LotR is relatively unchanged from the books, which is utter bullshit.
Sorry for the rant. I'm a bit of a fan of LotR and the Hobbit, both the books and the films.