Single player here as well and all I can say is how did you last two and a half weeks?
I completely agree, I stopped around half of epic and am not sure I'll go on. This is actually something I have experienced with DS2 as well, though I did complete the second difficulty there. Simply put, there's not enough there to hold my attention now that I've completed the first run, so yes, we do agree.
Oh and one more thing - I have been having a terrible sense of deja-vu while playing this game, it reminded me something awful about DS and DS2. I actually found it somewhat annoying.