Evaluate "A Vanity of Human Wishes" by Samuel Johnson as a satire.

Johnson's most famous poem is a satire, and is explicitly modeled on the tenth satire of the Latin poet Juvenal. Yet, if we look closely at Johnson's technique, it appears different from that of the other writers from his period (and slightly earlier)—Jonathan Swift and Alexander Pope—who were considered the chief satirists of the age, and also differs from other works we typically regard as the best examples of satire.
Usually, a satire uses devices such as irony and allegory to get its points across. For instance, in "A Modest Proposal," Swift uses a persona who literally expresses the opposite view to the point Swift is making about the extreme poverty of Ireland and the callousness of the British ruling class about it. In a much different style, Pope in The Rape of the Lock ironically uses both the language and background trappings associated with epic poetry to describe the trivial and silly goings-on among fashionable young people of his own time.
In both of these cases, there is a deliberate distancing of the writer's surface style from the underlying message, and though the intention is a grim and angry one (for Swift especially, concerning the outrage over human folly), the overall effect is darkly comical.
In "The Vanity of Human Wishes," Johnson presents his critique of mankind in a much more straightforward manner. He enumerates one instance after another of human folly, but does so literally, as if his intention is to tell "just the facts":

Enlarge my life with multitude of days,
In health, in sickness, thus the suppliant prays,
Hides from himself his state, and shuns to know,
That life protracted is protracted woe.

Obviously there is nothing comic about this, even grimly comic: it's just grim. It does not give us an ironic account of the unpleasant features of "protracted" life, but instead makes a literal statement about it.
Johnson was a deeply pessimistic man. The same was true of Swift, but Swift was possessed by a rebellious, anarchic tendency expressed in an outrageous style in the works for which he is best known. Johnson holds mankind up to ridicule, but in a more sober way—which some might say makes his message at least as powerful if not more so.