Just the enormity of the task and the different hats you have to wear when you are working solo, and then when you are nearing completion, there is the whole marketing angle to look at. It does not matter how good your book looks, without a following willing to back it, it will go exactly NO WHERE. I've included a shot of my cover done by the great Bart Sears, with colors by me.

@Just Peachy I came at writing my first GN script with novel writing in my head...waaaay too much backstory, world building and details baked in...you have to find a way to pare that down while keeping a coherent story, and also drop hints of the wider world along the way for more engaged readers...