I just got my rulebook! Since there's far too much stuff to list (not to mention the fact that I just got it an hour ago), rather than list all the changes, I'm going to let you guys ask questions, and I'll look up the answers.
Some interesting things I noticed during my first flick-through:
Reassuringly, there is a HEAVY focus on the older models as well as the new stuff
Plenty of pictures of upcoming models!
There are various "special' strikes for different types of hand weapons
Profiles in the book (apart from those models that are released on saturday):
Rivendell Knight Captain (with picture in the book)
Captain of Erebor
Grim Hammer Captain (with picture in the book)
Gwaihir (new model, likely plastic)
Knight of Rivendell (with picture in the book)
Warrior of Erebor
Great Eagle (new model, likely plastic)
Hunter Orc Captain
Gollum (new profile and new model)
The smaller rulebook contains 112 pages and has no profiles.
There are seven new army lists for Warbands, as well as a revised White Council list.
In addition to those listed, there's pictures of a new Elrond in armour and an alternative Radagast model.
Gollum gets a completely new profile, Elrond and Radagast remain mostly the same but receive some updates, Gandalf, Saruman and Galadriel don't change. Balin has a new profile but it's listed as "Balin the Dwarf" rather than Balin, Son of Fundin, meaning both profiles remain valid.
That said, let the questions begin!