If memory serves....wasn't there a battle at Osgiliath (sp?) that happened before the Council of Elrond? Could PJ just have moved that encounter? I don't have my source material with me today!
But I didn't mind Faramir taking Frodo to Osgiliath.
There was. Boromir talks about it at the Council. The Witch King feinted to test Gondor's defenses, and Boromir denied him the passage - a foothold on the western shore.
Jackson seems to have moved the battle back and drawn Faramir and Frodo into it.
I actually enjoyed that and I did not think I would - mainly because I was enthralled with getting to see the ruins of Osgiliath and the escalating War of the Ring take place there.
I think the only problem is what others have pointed out - Faramir changes his mind a bit abruptly. I think it would have been more compelling to see a more conflicted Faramir deciding to take Frodo back to Gondor but torn in his mind and heart about it, revealing the differences of his character from Boromir's. We really don't get that in the movie, even if he does make the right decision in the end.