It is always so much easier to discuss what they got wrong than what they should get right.

Yes it easier. Several of my points became much more important to me when I saw hints in the trailers that they were not getting it right.

Fortunately enough of the book survived in the first movie to make me confident in the second and third.

You are much more optimistic than I am. Oh the main plot will be there in some form but I am not at all confident about the details. Obviously, they will go through Mirkwood, visit Beorn, pass through Dale, and such. But will there journey be made more "exciting" (in other words violent)? Very likely. Will we get Bilbo's sense of horror at the battle of the 5 armies? Or will he be Bilbo the warrior hobbit? The two things that bother me the most are personality changes in characters and added violence/action. I think it is really important that the characters and amount of action are true to the book.