I reread Knaves' Wager, one of her earliest. Her later novels are somewhat more complex plotwise, but this early novel indicates Chase's strengths. It provides characters and conflicts that are resolved through more than an abrupt death or sudden change of mind, both the equivalent of deus ex machinas.
Loretta's characters are clever; her problems demanding. The set-ups demand clever and demanding resolutions.
In terms of character growth, she does a decent job with her "knave," Lord Julian Brandon, who comes to realize how much he wants to seduce widow Lilith Davenant and spend time with her, even to the point of discussing...drainage!
Her heroine, strong-minded and somewhat regal and more than a little shattered by her past marriage, is likable. Strong-minded heroines will come up again and again in this list. If they have reasons for their strong-mindedness, including their fundamental personalities, they are far more likable than if they are operating within some kind of slated role. Chase's strong-minded women are always well-rounded characters.
In fact, my favorite Chase is Mr. Impossible, which takes place in Egypt, involves a rascally hero and a smart, strong-minded, somewhat tunnel-visioned heroine (in the Temperance Brennan tradition). It delivers hilarious dialog alongside a Rider Haggard adventure.
Chase brings home to readers that romance is a story; it is an art in its own right.