The biggest disappointment for me so far is the railroading in terms of exploration. Hardly anything you can climb, and if so only very narrow spots, swimming, canoeing etc. is not available, no logging of trees getting you over a river etc. Whatever you can think of, you can do it was the advertisement. Well, my hopes are not very high any more...
Climbing would really have been a VERY good feature in the game especially with the verticality.
I still have nightmares of my characters falling in the spiders nest during the fight versus Dror Razglin and that are unable to re-join the battle. Spider climb / Fly / Ropes and climb would have been really good with such a verticality.
I personnaly don't mind at all about being able to swim and canoeing in a heavy armor... But more interractions with the environment would have been very cool (like as you said logging trees, cutting bushes to find new pathes,...).
