I got the sample of it on my Kindle last night and liked it, so I bought it this morning, and I'm so into it, I probably could have stayed in bed and read the whole thing today, but I had to make myself get up and do something more productive (like get on AC - you know).
Anyway, reading it, I was like, "OMG, that was me ten years ago!!!" I was not quite as socially anxious as Cath, or I just hid it better and forced myself to meet people and do things to overcome it, but that whole scenario of going off to college by yourself and living with another person you don't know and wondering how you're going to find time to keep writing fanfic, which you don't want to talk about to anyone outside the internet because you know they'll think it's weird... that was so me! Like you said, Steph, it was very refreshing to read about a character who is like us and who shares our hobby. I've never read about a fictional character who writes fanfiction in a published novel.
Also, I think the Simon Snow/Harry Potter thing is funny. I am assuming the author used to or still does write HP fanfic, probably of the Harry/Draco slash variety.