I agree wholly with CSteefel, PJ did a disservice to Frodo in the movies. Frodo is a very brave character throughout the books, but PJ turned him into a snivelling, whining basket case who has to be dragged by Gollum and pushed by Sam to Mordor.
Examples:
As I often say, PJ took away Frodo's finest moment at the Ford of Bruinen. In the book, he faces the wraiths across the river, draws his sword and says "By Elbereth and Luthien the Fair, you shall neither me nor the Ring." PJ has him in a stupor, wheezing in Arwen's lap. Cute, but not impressive.
On Weathertop, in the book, Frodo charges the Ringwraiths and manages to stab one (the Witch-King himself unless I am mistaken). PJ, again, takes away his fire and has Frodo whimper, drop his sword, run away and trip over his cloak. Pitiful, just pitiful.
And Book Frodo would never had chosen Gollum over Sam or told Sam to go away. To me that was the greatest travesty of any changes to the story.