Honestly? Legolas and Tauriel should have been cut. Gandalf's Dol Goldur adventures (with Saruman, Galadriel, Radagast, and Elrond) should have been cut. Stephen Fry and Alfrid should have been cut. Bard's family should have been cut. The movies would have been much better off if they had focused exclusively on the Dwarves and Bilbo, with bits of the Elves and Bard scattered here and there.
The biggest problem that I have with these movies is that they're so damn bloated. A taut, tight journey following the core characters would have resulted in a far better series of films methinks.
I didn't mind Legolas. I think that he's an interesting addition and is a fitting Elf to include as a main character. He's a fantastical character, represents a lot of the childlike wonder I remember from the book. He's a great callback without going overboard. He fits into things like that escape scene really well. I think that everything else is the problem. I think even the heavy focus on the Dwarves as individuals is a problem. There's no way people are going to be able to keep track of them all in film format. They should've been depersonalized into one group unit. It should've been Bilbo's Journey featuring Wise Gandalf, The Dopey Dwarves, and Legolas Kicking Ass. Instead it's Fight For Gold Mountain.