There's a lot to like in Battle of 5 Armies, as it's probably the strongest entry in the Hobbit series... That said, it (and the others in The Hobbit series) just don't measure up to the Lord of the Rings Trilogy.
Featuring plenty of battles, a return to a beautifully rendered world, and top-notch special effects, it's only real flaw is a disconnect with the characters that just didn't exist in LotR. Certainly, there's some characters here that you'll enjoy, but where LotR seemed to be flowing with tons of characters you quickly grew attached to, the same cannot be said for The Hobbit.
One also has to be disappointed in the dwarf/ elf "forbidden love" that is so incredibly forced, the movie itself never seems to take it seriously. Even if the extended version somehow made it "better" the whole thing was laughable, at best. The 2 characters involved seem ready to leave their entire races to be together, yet there's never a moment between the two that makes it seem they ever fell in love. It was hard to swallow throughout the other films, and 5 Armies never fixes this. I cringed every time the 2 actors shared scenes, not because they were bad actors or didn't make me believe they had feelings for one another, but I could just never buy into the fact that these were living characters that fell in love and not just actors playing the role because it was written that way.
Now, I wish I could give more info on the differences between the standard edition and this extended edition (Bot5A earned an R-rating in its extended format, a first in either series, but I don't recall any scenes in Bot5A that stood out as any more excessive than any other of the films) but, I learned a long time ago, beginning with King Kong and the Fellowship of the Ring, that Peter Jackson consistently offers better movies in his extended versions- at times, cutting scenes that I felt were excellent (but didn't really add to the story, per se) and added wonderful fan service to the viewers, all in the name of saving time. Taken as a whole, they may be added scenes of fights that don't forward the plot, but they most definitely add action to the, well, action-centric films.
I've given it a 4* rating, only because it deserves a rounding up from what I think is a 3 1/2* film. If you're a fan of Middle-Earth, there's absolutely no reason not to add this to your collection, especially in its complete version. While I may never enjoy the Hobbit movies as much as the Lord of the Ring films, I'm glad these were made, and glad they're a part of my collection. As a fantasy/ sci-fi/ horror buff, these will be some of the first "grown up" films I introduce my kid to as he gets older. They're safe, overall, and very "cool". Comparatively, where the second trilogy of Star Wars fell almost completely flat, the Hobbit avoids that same measure of failure.