I have now read all of the Agatha Raisin novels in the series, this being the 17th! Yes, they are light and easy reading and not to be taken too seriously. They are all equally enjoyable. In my opinion none stand out in particular as the 'best' or 'weakest'. Ideally, they should be read in order of publication, to follow the development of the characters.
Agatha is entertaining and doesn't she remind us, just a bit, of someone we know? A holiday read, a bedtime read. I don't suppose it will ever be on the A' level English Lit syllabus!
Agatha, is funny, politically incorrect, independent but at the same time vulnerable and human, especially where men are concerned!
Read and enjoy. (And if you do take to Agatha try Hamish MacBeth by the same author.)