As others have already noted, a lot of the language is quite difficult (I freely admit that I still have to look up the occasional word when re-reading the Chronicles, lol.) The main protagonist is not the standard, heroic figure I expect from a fantasy novel - he's far too complex for that. The pacing of the Chronicles was also more measured than I was used to, requiring more patience and commitment from me than I had previously given to my reading.
But the only challenge which actually brought a halt to my reading - at least for a time - was the events I noted above.
Oh, and I've read three of the Dark Tower books, and alot of other stuff by King. Almost unfailingly - in my experience anyway - King manages to produce a 'happy ending'. It, The Stand, Christine, Salems' Lot,... I know, I know, he doesn't always do it (the Mist), but more often than not, things work out for the 'good' guys, and the 'bad' guys are defeated. I found this pattern of writing far easier than the Chronicles,
Spoiler
where I honestly didn't know whether Covenant would eventually prevail against Foul, and himself, or not.
