A Midsummer's Night Scream is clearly a continuation of the slow downward slide in quality that began with Bell, Book, and Scandal, and ends with the horrible The Accidental Florist.
Bell, Book, and Scandal had, I think, only one change in viewpoint. A Midsummer's Night Scream had several changes in viewpoint, mostly from Mel's view, which is unusual in this series.
Despite the series name, A Jane Jeffry Mystery, Jane had almost nothing to do with solving this mystery. In fact, most of this book revolved around tasting testing caterers and attending a needlepoint class. Since neither the caterers nor the needlepoint class had anything to do with the mystery, their constant presence in the story was distracting and served no purpose in advancing the story or the mystery.
Unlike previous mysteries in this series, Jane does very little thinking about this mystery. In fact, she does almost no thinking about the murder, potential motives, or potential guilty parties.
The oddest part of this book: the epilogue. No previous book in this series has ever done a "where are they now" ending to the story. It was out of place, not remotely entertaining, and again, not from Jane's viewpoint. None of the "where are they now" statements would be anything Jane could possibly know.
Jill Churchill, if you are tired of writing this series, just stop. Don't try to wrap everything up neatly for Jane as you did in The Accidental Florist. Just stop writing.