Interesting things to note:
1) Book 3 is entirely about Aragorn, Legolas, Gimli, Gandalf, Merry, and Pippin. For over half the book, we have no idea what is going on with Frodo and Sam.
2) In the movie, I preferred the sections about the Sextet over the Frodo/Sam sections. In the book, I am finding myself more invested in the Frodo/Sam sections over the Sextet.
3) I am not sure why the movie did the whole "Attack of the Wargs" followed by "Aragorn is DEAD!!!"
4) On one hand, I get why, in the movie, the Elves arrive to Helm's Deep. On the other hand, it's way out of the way and wouldn't they have walked right past the attacking Orcs and Uruk-Hai??
5) While Tolkien is incredibly realistic with this book (particularly the ending), I found the Saruman-Gandalf banter to be rather juvenile. Bad Guy is BAD! Good Guy is GOOD. Good Guy says something smart and makes Bad Guy look dumb. Bad Guy is ENRAGED.
All in all, rather insightful.