This is okay for a quick read. I wasn't enjoying the longer book I'd been reading, so decided to read this before bed for something different.
I liked the main characters, enjoyed their storyline - young lovers who split up and then reunited after five years. (In my own reading and writing, I've noticed that's a storyline to which I'm drawn.)
I also liked the London setting, the descriptions brought the city to life for me.
But I found the frequent mentions of the sister to be annoying. In general, not a big fan of the best friend/sister thing. The sister kept being mentioned, even when it didn't seem necessary. Things like, "He had a nice apartment, his apartment reminded her of the apartment her sister's boyfriend owned."
I would have rather the focus be on the two main characters - not the sister and her boyfriend - who I understand were main characters in a previous novella by this author.