This game definitely needs an expansion to include more peril and corruption cards, more quests, perhaps specialised minion combat decks.
Not to mention it would be nice to have a two player variety that increases the turn length for two player games so that the Fellowship move their marker only one space and the enemy have special cards to deal with that kind of game. At the moment 2 player games are very imbalanced and dont run very well.
It definitely needs a better ending - fighting the dark riders is not nearly exciting enough - maybe the witch king would be better as he comes so late into the game he is hardly used at all. He should definitely be made more use of in the finale. The finale would also be far better as well if you had to keep your hero and the enemy in their final game state before they do the final battle - its just too gamey removing all their damage etc. And also the rule to defeat the minion- means all Sauron can do is play defensively - there no point attacking at all as the hero has far too much health to be defeated. This should be changed to enable defeating of the hero (although obviously story wise there would need to be some significant reason why defeating the hero would enable the dark side to gain a significant advatage in middle earth - perhaps the fianl battle should rope all the heros into one big fight against the witch king and his men for example).
I would also like the possibility of bringing in characters on the enemy side through corruption - for example being able to bring in new minions as Saruman and Theoden etc if they are highly corrupted would be a good idea. The heroes should be able to perhaps buy in more characters for consulting with or something using favor or by successfully exploring a certain area and these new characters should be more geared to providing magical items or abilties etc not favor.
Also favor runs very short in some games if the cards go against the fellowship, there should be some way of getting more favor for example certain going to Havens or certain areas on the board such as the Shire should give you automatic favor as a reward for travelling out of the way - it would open up the game more as well instead of having it concentrate around Mordor.
Just some ideas.