Talal on 09 January 2015
Getting the controls is a big part yes, but it's also unforgiving in that enemies deal a lot of damage and you're usually bombarded by enemies. One hit and you're pretty much done. But I don't consider the controls clunky at all.
Edit: I think most people consider it very difficult because you will die to random enemies a lot! With most games the non boss enemies are just there for you to farm and kill til you get to a boss. With Dark Souls getting through some areas is just as hard if not harder than bosses.
