I have so many mixed emotions with this book... there were elements that I loved, and others that I didn't. 

There was one plot twist that I was not expecting but loved how it came out. 
Also I need to know WHAT CALLUM IS! 
The ending wasn't exactly what I expected either, but I wasn't disappointed.

OK now the rest of this is quiiiite spoilery.

Here's the thing people can harp on about how we "knew the joining was coming" but we also knew that not all cases of the joining went... further, I feel like JLA added that as fan service and I don't even feel that scene was even well written, it felt tacky. 

Poppy and kieran had always had a bond that is true, but sorry my guys it never went past platonic love, there wasn't any sexual chemistry there so for JLA to change their dynamic was just not it.
Even before they got Cas back they were both acting overly coupley and it honestly gave me the ick the whole time reading it.  
For me it completely ruined the bond they had originally developed and diminished the "soul mate/ heartmate" bond between Poppy and Cas.
Yes Cas teased poppy about sex and would do it infront of Kieran as banter, probably because he knew it wouldn't happen and he trusted kieran around her. 

I can definitely see where people get the impression that it's become more of a poly/throuple kind of relationship now though- casually sliding into bed with poppy and cas whilst they were sleeping? Come on.

So imo if I could redact the events after the joining, scenes where Kieran is acting like he is poppy's husband (when other characters mention it then you know that your husbands best friend/ for all intents and purposes bloody brother is overstepping a few lines) and then any throuple-y scenes, scenes where poppy was pining for kieran, then it was a good book. 

Sorry JLA but I know fan service when I see it and this was a prime example, how nobody sat down with her and questioned why she had changed the entire dynamic between poppy and kieran I will never know.