Frodo seems to catch some of the most flack for being a badly written and portrayed character in the films. I have to say, though, I think Jackson et alia wrote the part well, but this is one of the times when the choice of actor (Elijah Wood) was not good.
I mean there is the part on Weathertop when Frodo falls down right away, and doesn't show any of that "elvish" courage to make a strike back, but all-in-all, I thought the part was well-written. In The Shire after finding out about the Ring, he quite confidentally takes it, asking "What must I do?" In Rivendell, of course, he stands up amongst the squabling elves, dwarves, men and a wizard to say "I will take it." (The expressions from everyone at the council too, captured the purpose of having the small one amongst warriors and wise-men saying "I will take it.")
There is also the event of Frodo sending Sam away, but I have some thoughts on that, after hearing from others.
And can't forget the end of TTT where Frodo waltzes the Ring right up to the Nazgul, in Osgiliath, but that creates more of a major plot hole than actually being a problem with Frodo's movie portrayal. But, I'm also looking at it from the standpoint of trying to show the Ring gradually breaking down Frodo, and changing him. I think that was scripted well, but did not come through the best because Elijah Wood gave a pretty weak performance. I mean the lines were there, for Frodo to show that famous courage in the books, but the actor came up weak and unconvincing.
Some other things of note, the Frodo-Gollum relationship from TTT thru ROTK was great, a lot of which had to do with Andy Serkis. Were you getting the feeling Frodo was not only pitying Gollum, but Gollum physically represented what was quite literally happening to Frodo, or what Frodo felt was happening to him, because of the Ring? Maybe it's just being familiar with the book plot, and it's not something that overtly came through in the films, but I was feeling the dread and terror of Frodo recognizing:
1. What the Ring made Gollum and...
2. What the Ring was actually doing to Frodo, and understanding Gollum on a level that Sam, nor any other non-ring bearer could.
So, I think I rambled enough, let's start there and I've got some more fodder to throw in and we see where this goes.
