As for Faramir, the worst part about his storyline to me - taking the hobbits to Osgiliath - can be explained through the changes to Frodo as he wasn't particularly trustworthy (this essay gives a nice discussion on that). However, I didn't like how he was almost corrupted by the Ring, and I thought - given the changes to Frodo - it was foolish for him to let Frodo go after seeing him almost give the Ring to the Nazgul.
