From the first page, it is evident that this isn't Tamora Pierce, Patricia C. Wrede, Mercedes Lackey, Sherwood Smith, or even Trudi Canavan calibre of writing. That being said, fans of the aforementioned authors will enjoy this novel for what it is: a piece of light fiction.
Poison Study does well in the plot department. I don't think I've ever read a book in which a food taster is the protagonist and an authoritarian leader is a sympathetic character.
On the other hand, I felt Poison Study fell flat when it came to the romantic relationship between the two main characters. There is undeniable chemistry and a veil of mystery (a la Court Duel by Sherwood Smith) but any romantic scenes are described in such abstract terms that you're not sure if the characters kissed, let alone did anything more interesting!
I look forward to reading the sequel, Magic Study, with the hopes that the auhtor's style will have matured in her sophomore effort.