Well, not that you need my two cents, but here it is anyway.
Extra spoiler warning:
You've already covered the differences that I thought missed in the film: Aragorn's ride off the cliff and rescue by a stay horse (the purpose of which seemed only to be that he could see the approaching Orc army) and Faramir's desire to take the ring back to Gondor... and the battle at Osgiliath. Don't know why PJ thought we needed to
see that battle, especially since Sam, Frodo and Gollum were never there and it's supposed to take place later, but there it was. I was most disappointed by Faramir's changes, though. I kept thinking,
but he didn't do that. There's a
reason Faramir's dad acts as though he dislikes Faramir... he's
different from Boromir, and I think that needs to be shown.
Anyway, I liked how the film characterized the Ents, but since the Ents are such un-hasty people, PJ had to speed them up a bit, so no trek to Treebeard's home, no Entdraught, no days-long Entmoot, but I did like Treebeard's reaction to seeing the Orc encroachment on the forrest facing Isengard. His shock and anger were obvious and immediate, and I loved his call to the others.
Re: the cloak pin, I liked PJ's solution to having Pippin escape for an extra couple minutes simply to throw it in the grass. It's just like Orcs and Uruk Hai to miss seeing that pin dropped on the path among them like that. Plus it's simply more believable, more like a human, for Aragorn to find it in the path, trampled, than to suddenly see a stray footprint off the trail and go searching in long grass for a green pin. I think it was enough for PJ to show Aragorn listening to the ground to tell him that the Uruks had sped up as an example of his extraordinary Ranger's skills.
There's more, but I have to get to work now.