The only thing that really bothers me with fanfiction if it's a bashing fanfic. I'm pretty much either neutral or interested in other types of fanfiction.
I will admit I do become disappointed if a fanfic is not completed, but it's really up to the author whether or not to continue them. Things can come up and the author could either lose interest in the story or no longer have the time to work on it.
As for slash fanfiction, I'm pretty much neutral towards them. They used to make my blood boil, but I got around to reading a few slash stories and found they weren't as bad as I thought they were.
Interesting that you brought up Out of the Shadows. That fanfic was originally going to go a bit more in depth in slash, but as I typed it, I kind of forgot about it. Any mention of slash exists I think only around the middle of the story and is reduced to a few sentences, and disappears from the story as it advances.
Hm..I wonder... would this topic go in After Midnight? Or is it all right where it is?