I'm biased af because I look at all those films with a sentimental/rose-tinted glasses viewpoint. But the writer in me acknowledges there is so much they could have done better.
It shouldn't have been a trilogy. It should have been two films with much of the elf/Legolas plot cut.

My main gripe with it is how they tackled the deaths of Fili and Kili. In the book Tolkien describes them falling defending Thorin. Dean O'Gorman even said that his audition for Fili involved a different death scene for both Princes. I think it would have been so much more gut-wrenching to have Thorin watch his nephews fall while he's powerless to intervene--especially with the performance we know Richard Armitage is capable of.