Don't tell anybody, but I totally read the first half of this book when I should have been working. I started it in my morning free time, then just... kept going. >.> There's inherent tension built into coming out stories, and it's one I thoroughly enjoy, even when it's done poorly - and this book did it EXCELLENTLY. I did have to take a break about two thirds in because it was too many feels for me, but picked it back up and was duly rewarded with a lovely resolution.
It's a quiet book, full of subtext and musings, which balances out the stark emotions involved in first love and coming out. The earnestness of the leads, which can, when wielded by lesser authors, read as simple or disingenuous, is balanced out by normal human flaws and mistakes, but not enough to rob the book of it's sheer hopefulness.
And, as others have said, the sense of place was PHENOMENAL. I've been to London a few times, which perhaps helped, but not to any of the places mentioned, so perhaps not. And it wasn't just the metropolitan locale - even the living spaces felt very real, and done without overbearing descriptive prose.
My one piece of concrit is relatively subjective - It got very referential in the last third-ish, with thick paragraphs and significant dialog about books, movies, music of the time. As someone who wasn't familiar with any of the references, I was... the best way I can put it is that I felt left out. I didn't know what the cool kids were talking about, and I could tell that it was very important to the character development but I didn't know specifically why. It's utterly realistic, though - As a queer person coming out in high school in the 90s, my courage was vastly dependent on the music I was listening to - so I'm not mad about it. Just wish I'd been part of it, you know?