t’s not often I like mysteries but if it’s mixed with romance then yes! I adored Ethan and Maggie (though Maggie was kind of mean to him at first, in my opinion, for not really any good reason). The mystery parts were good, too. Mostly because I like things involving poison and secret passageways. The whole assembly of family in this locked room mystery were full of quirky eccentric characters which made it fun. And, having read Ally Carter before, I knew I liked the relatable writing style. 
My one drawback was the whole “Christmas” aspect was a little forced, even though it was a fun idea.