Office consensus: The Faramir tweak was not good, although I'm hopeful he'll be developed more fully in the next movie. Wargs rock so does Gollum. The Ents were excellent to look at but their indifference was irksome. Theoden and Aragorn seemed weak (I don't share that opinion). Overall, PJ should have stayed closer to the book with details such as who was at the Deep, the life and times of Eomer, etc. But bottom line, we all loved it.
I am a fairly avid purist myself.
I am not saying I would have done the movie as Jackson did. I would surely have hewed closer to the text. And I wonder if I would have made as compelling a movie for the average filmgoer.
In the end, I understand as a matter of dramatic arc why Jackson made the choices he did. I think nearly all of them are very defensible from that point of view. In the end you have to evaluate everything Jackson does by the standards of what makes for a compelling movie for a general audience - not total fidelity to the original text (much as I would love to see the latter). To film a completely faithful Two Towers would not only require a lot more screen timne, but it would have too many dramatic climaxes, robbing each one of its power. Have the Ents show up at Helm's Deep and you take away the climactic power of the storming of Isengard. Have Shelob put in (in this movie) and you take away from the power of Helm's Deep. And so forth.
I think that the greatest quibble is really Faramir's character. I did not mind the Osgiliath sidetrip (a spectacular set and scene that made up for my annoyance with the liberty taken) so much as I did the sudden reversal in his decision to release Frodo. I think just a bit more time spent on him and some display of inner turmoil over what to do with Frodo would have made for more compelling cinema.
I think what we Tolkien Purists must admit is that our experience of these movies is inevitably going to be different than that of the general audience, and in fact out deep familiarity with the text may be a never completely penetrable barrier to our enjoyment of them.