More 2.5 stars, but the accompanying fanart pushed the rating up.
To be honest, I'm not really a sterek fan. I've read a good handful of stuff, but none of it really wowed me like the stuff from other fandoms. Occasionally, I read a blurb that sounds interesting enough to give sterek another go. Cornerstone was a good story. It was a pretty good story up till about 30,000 words, and then it just felt long after.
The story involves the relationship between ex-marine Derek, who suffers from PTSD. He opens a bookshop in Beacon Hills, where he meets a blind Stiles Stilinksi. Their relationship doesn't start off very well, but they quickly become friends. Then friends with benefits. Stiles wants to "experiment" with Derek and Derek agrees to things like kissing, to handjobs, and eventually flat-out fucking.
I should also warn that I'm not the biggest fan of contemporary stories where there's no action or suspense. Cornerstone is a story about two people who learn to become lovers, and that's pretty much it. It was well written, yet felt like it dragged.