If ‘Voyagers’ could be said to provide an overarching theme, it's a theme with a cautionary note about time travel.
The best-known entry is David Masson’s ‘Traveler’s Rest’ (1965), about a planet where time travels faster the more closely one approaches the equator. While the concept is certainly imaginative, the story’s prose is overly dense, and suffers from some contrivances; for example, author Masson uses a deliberately clipped style of dialogue when recounting events in the northern latitudes; once his character moves further south, conversations become more expansive.
Another of the better entries is Michael Moorcock’s ‘Flux’ (1963), in which troubleshooter Max File is sent forward in time in an effort to save a dysfunctional European Union from collapse (a concept quite prescient when regarded from my vantage point of 2012).
Editor Silverberg’s ‘Absolutely Inflexible’ (1967) takes an ironic look at preventing paradoxes. Larry Niven’s ‘Wrong-Way Street’(1965) is a middling tale of an astronaut who tinkers with an alien spaceship.
Wilma Shores’ ‘A Bulletin…’ takes a humorous approach to time travel; when a contemporary scientist succeeds in snatching a witless Everyman from 2061, back to his laboratory in 1961, frustration ensues.
Some of the Old School tales hold up rather well. P. Schuyler Miller’s ‘The Sands of Time’ (1937; travel to the age of the dinosaurs), William Tenn’s “Brooklyn Project’ (1948; tampering with the future might change the present), C. M. Kornbluth’s ‘Dominoes’ (1953; exploiting stockmarket data from the future), and Poul Anderson’s ‘Time Heals’ (1949; cryogenic preservation) all are reasonably interesting.
The less impressive entries include Alfred Bester’s ‘The Men Who Murdered Mohammed’ (1964), which suffers from too forced an effort at humor. Lester del Rey’s ‘And It Comes Out Here’ (1950) adopts the rarely used second-person narrator, but this only burdens an already clumsy plot.
The verdict ? Of the 11 stories in this anthology, there are several worth reading. This may be enough justification to pick ‘Voyagers’ up from the used-book shelves.