I have mixed feelings on this one. First up, there are lot of things I loved. Steph for example - she's nerdy and funny and I already loved her when I played LiS: True Colors. (I didn't play Before The Storm, but that wasn't a problem for me.) I liked the writing style, it fit Steph well, I think. There are a lot of pop cultural references, there's no purple prose, but at the same time there are well said sentences that made me feel something (though I can't say if this is because of the intonation the sentence had in my head or if others would think so, too.) Steph's friends were great and I loved how diverse the cast was in general. 
It was great to see Izzie and Steph get to know eachother. In the beginning they were really sweet together. 

However, I wasn't that happy with how everything developed. The book takes place over the course of two years, but in my opinion it doesn't dive deep enough into the characters and relationships dynamics to feel that way. Instead, it feels like there should've been more scenes between the two where they talk about their needs/wishes and also a few more scenes that show why they weren't just initially attracted to each other, but stayed together this long. Because of how short this book is, you don't have time to grow with them and they never seem to leave a state of "being attracted to each other, but not knowing much about the other". It seems like the time span is way shorter than it actually is.
I get that miscommunication is a big part of the problems they have and I get how that came to be, but I would've liked for them to have the chance to turn it around by giving them a conversation that goes deeper that the ones included. It would've given their relationship more depth and would've made their struggle more impactful.

I do think this is worth a read if you're interested in LiS and specifically Steph. It just wasn't as good as I hoped it'd be.

All in all, I really liked Stephs character arc though. The way she's shown in the beginning, this nerdy life with D&D, Critical Role and the café, how all of this disappears over the course of the story, because she starts doing what she thinks Izzie will like. How she kind of "adapts" to Izzie in a way, because she's so fascinated by her and doesn't want to lose her. That was very well done in my opinion, as well as Steph finding out that she lost herself in the process.