In the New York Edition preface Henry James proclaimed The Ambassadors as the best of his novels. Critics have generally agreed that it ranks high in the list of his achievements, though E. M. Forster and F. R. Leavis have been notable dissenters. James's evocation of Paris has gained many plaudits, as the city becomes a well-realized symbol of the beauty and the sorrow of European culture.
Critical controversy has swirled over Strether's refusal of Maria Gostrey, with some seeing it as a perverse rejection of his best chance for happiness. Others have said that Strether, whilst a great friend of Maria's, is not in love with her, and that the couple could not have made a successful marriage. Critics also have speculated about whether or not Chad will heed Strether's advice to remain with Marie, or if he will return to America for the substantial rewards of family business – their general verdict is that Chad will follow the money.
In a letter to a friend, James said that Strether bears a vague resemblance (though not facial) to his creator. It is true that Strether shows an ability to grow in understanding and good judgment, although some critics have seen him as limited and timid, despite his European experiences.
A continuing literary mystery is the nature of the "little nameless object" made in Woollett. Strether calls it: "a little thing they make—make better, it appears, than other people can, or than other people, at any rate, do"; and he calls the business: "a manufacture that, if it's only properly looked after, may well be on the way to become a monopoly". In an article in Slate magazine, Joshua Glenn proposes that the nameless object is a toothpick, while other critics have proposed matches, toilet articles, button hooks, et cetera.
In 1998, the Modern Library ranked The Ambassadors 27th on its list of the 100 best English-language novels of the 20th century.