A few years ago, I read the first book in this series, and when I came across this one, I couldn't remember why I hadn't continued the series. Now I remember. I would not say this is a bad book necessarily, but it did have some features that contributed to the low rating. First, the late Mr. Pargeter (having been deceased for a while and leaving his widow, our protagonist, well off) was mentioned on nearly every page. To be fair, there was a stretch of two whole pages where he wasn't mentioned. At that point, why not just make him a living character? Second, the premise for Mrs. Pargeter investigating into the murder was flimsy to say the least. She must have a spidey-sense for detecting foul play. Third, during the reveal, the author tries to hold the audience in suspense by repeatedly referring to that person as "the murderer" rather than by name. This is similar to movies/TV using forced perspective so we can't see who the killer is, except it doesn't work in books. Lastly, the amount of coincidence that leads to the reveal makes one wonder how much of Mrs. Pargeter's successful deduction is down to luck rather than any abilities she possesses.
To be honest, a few years from now I'll come across the third book in this series, and, my memory having been dulled by time, will probably pick it up and read it, not remembering why I didn't before.