James Hadley Chase wrote around ninety thrillers over a period of over forty years, often producing as many as three a year. If you like one, you're likely to enjoy all of them, since he hardly developed as a writer.
His strengths and weaknesses are present from the beginning. He was strong on plot, pace, and violent action; relatively weak on originality and character; and an indifferent stylist (compared, for example, to Raymond Chandler, Ian Fleming, or Graham Greene). He was a British author resident for much of his life in Switzerland, who nonetheless wrote mainly about American scenes and people. His books often read as though conceived as screenplays, and Hollywood thought well enough of him to film over fifty of his books. The book in question is not one of those.
'Well Now, My Pretty', originally published in 1967, is a straightforward crime thriller based around a casino heist, set in Florida in the mid-'60s. Chase was by this point in his career an expert at sucking the reader in; the rather derivative plot grips from the beginning, and has enough twists and turns to maintain interest, without ever being genuinely surprising. Chase is good on the ways in which weak and naive people can be drawn into criminality by amoral predators, and how evil corrupts everything around it. He's less good at creating characters who have a third dimension, or at avoiding clichés; and he has a weakness for improbable plot devices. For me, this will always limit him to the second rank of thriller writers.
A brisk, disposable read. Readers looking only to taste a single Chase would probably do better to seek out 'No Orchids For Miss Blandish' - published in 1939, when writing of this kind was still relatively new to the British public - which was the subject in 1944 of a famous essay by George Orwell, 'Raffles and Miss Blandish'.