There's an 8 page thread on this very subject in the FFG official LotR forums, opinions are all over the place generally, was a bit of an opening can of worms 
You know, it's so hard for me to remember those forums still exist, since 99+% of the Cthulhu traffic is here so I unconsciously assume that this is the case for other LCGs as well. Thanks for pointing this out!
After having looked at the thread there however, it contains very little discussion of what people think about the Arkham Horror game, it's mostly a combination of doom for LotR, complaints about the movies and Christopher Tolkien, and stuff like that. Not all that useful, I think the crowd here on Cardgamedb is still superior 
In the last few days I've been sampling a few LotR podcast episodes and locations definitely seem to be a recurring feature that people feel could be done better, and I'd already heard about issues with auto-include cards. I have some concerns with how this combines with playing two-fisted too, if you need certain auto-includes and you're playing solo out of a single collection, you're not going to have 6x copies. Now, maybe that many isn't necessary, but it may be an advantage. Admittedly, I'm still trying to shift mindset over from competitive (where any advantage matters) to co-op (where people often deliberately play weaker decks for fun) so I may just not be properly adjusted yet...
I'm not familiar with what sort of auto-loss cards different quests have, but it doesn't sound good. Is this basically just "you need at least X cancels" or are the requirements on the player deck more specific than that?
Earlier on I thought that it would be cool to use a system similar to Conquest where your Investigator comes with a set of their own custom cards and this can help compensate for not having 3 Heroes in terms of deck variety. However, now I am not sure that would be possible without a change to the distribution method. A LotR pack generally comes with 1 Hero who takes up 1 card slot, and a new quest which takes up a fair bit of space (I don't know exactly what the average is, but it's a substantial amount of the pack). Then what's left is player cards. If the hero took up 9 cards (as in Conquest) and the quest was about the same size, there would be too little room left for player cards, so this seems unviable unless you make other changes to help compensate. I still like the idea from a flavor point of view, but it may just be impractical if they keep 60 card packs and want to release new Investigators in them. If you keep Investigators for boxes it could maybe still work.