I finished the final book in the Shatter Me series. I really liked the first book because of the language and the mystery surrounding the character and her circumstances. And Tahereh Mafi did a great job creating a slow burn of information reveal. And as much as I dislike love triangles, this one was resolved the way I had hoped. It had a very Joey-Pacey-Dawson feel to it, honestly.
I would recommend the series, but not wholeheartedly. It would depend on how involved someone was in the genre already. If one loves the genre, then yes, give it a go. But if one were just a dabbler in the genre, maybe select some others to read first.