On the plus side, Mitchell comes up with some interesting storylines, then dissipates their quality in rambling narrative, tortuous dialogue, and simplistic psychology (particularly relevant as her sleuth is supposed to be a 'pyscho-analyst' with some some self-opinionated expertise in human psychology).
Give Mitchell credit, too, for introducing a female sleuth (before Marple shot to prominence), and making her a self-opinionated, self-confident, bloody-minded woman of the world rather than a retiring spinster.
So we have the usual murder - a murder mystery without a murder would be a corpse too few: we have a body (or most of it), it's unidentified, but we have a missing man, whereabouts unknown, we have the usual run of cosy suspects (from vicars to doctors to lawyers), we have a policeman who is prepared to operate on the periphery while the amateur detective gets free run of the investigation, and we get a lot of people with evidence, opinions and suspicions which they are often too keen to reveal, too ready to conceal, too capable of misrepresenting or distorting, too determined - or too shy - to voice.
And we get page after page of tedious conversation and dialogue more effective than a sleeping pill. Published in 1929, it's the voice of the English upper classes. Mitchell's father was Scots, he was a tradesman, she was born in Oxfordshire, she wasn't part of the English upper classes, she appears both aspirational and excluded.
If I were to begin psychoanalysing her writing, well, she certainly embraces a voice which is all English, Tory, Church of England, and Rule Britannia. Was that the voice of a woman excluded from society, was it an aspirational one ... or is there a hint of mockery?
Published in 1929, with Fascism on the rise, Capitalism plunged into chaos, and Communism part of the West's daily political curriculum, there's nary a political voice raised in the story, just obsequious respect for upper class culture and social norms.
Mrs.Bradley was launched into the market for sleuths before Miss Marple cornered it; is it significant that whereas Mitchell churned out over 60 Bradley stories, it's Christie's invention who would have the more impressive shelf life (and TV ... and cinema)? Christie was as obsequiously English upper-class as they come - Tory, C-of-E, Rule Britannia, God save the Monarch.
Mitchell's books are hideously over-written. Not a bad plot - she had an eye for a story, for a twist or two. Not a bad plot, but made soporific by page after page after page of people talking at one another. Mitchell has a habit of getting her creatures to make speeches to one another. She may have been a modern woman, seeking independence, finding a career in teaching and writing, escaping from that birthright of being born into trade rather than into the elite class, but the writing gets deplorably dated at times.
The language is all the patois of the upper classes (jolly hockeysticks, cricket on the green). Bradley does talk to the peasants - they see things - and we get regular abuses of language which make "Cor blimey Mary Poppins" seem like an authentic piece of working class characterisation. Forget yer actual sexism and racism, it's the self-righteous elitism of the English elites which really sticks in my craw. Reading this, I would quite happily have seen all the characters murdered.
Interesting plot, best to employ someone to wake you every ten minutes so you can continue trying to follow it.