Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Disappointing follow-up to the wonderful series debut

I loved THE PRIMROSE CONVENTION, the first book in the series, but was disappointed by SWITCHBACK. CONVENTION featured a wonderful ensemble of distinctive, endearing characters, teaming up to locate a missing man. The relationships among these characters were charming and unique. In SWITCHBACK, the main characters are fairly isolated from each-other for most of the book. The story centers around one of them, who is subjected to enormous suffering, partially caused (unintentionally) by another of the formerly-likeable characters. The unremittingly bleak tone is a misstep in my opinion; it didn't work for me. And the qualities that made CONVENTION special are mostly absent from SWITCHBACK. I don't object to a somber book, but this one felt "off." CONVENTION wasn't sappy-sweet, but it did strike a hopeful tone, and SWITCHBACK's tone was... hopeless.