I actually found it easier to read than LotR. Especially since, whenever I skimmed the Sil, I *made* myself go back and start reading again from the point where I started skimming. This meant that it took a couple of days to get started on the Narn I Hin Hurin.
But mostly it was the vast number of interesting little tidbits that kept me reading - I was able to go "Hey, so THAT's where that came from!" again and again. I truly believe that Tolkien gets better and better the more of him you read, because of the completeness of the world he subcreates.