Is it difficult to write a novel? Not to those who love writing. Is it difficult to write a GOOD novel? Hell, yes.
I recently took a novel workshop class (best move I ever made other than marrying Andy.) There were a handful of students in the class and we read each other's novels or parts of novels and critiqued the pages. The feedback I received was incredibly helpful. I am now re-writing at least the first 100 pages of my novel.