best/greatest thing since sliced bread

the best/greatest thing since sliced bread (humorous)

if someone or something is described as the best thing since sliced bread, people think they are extremely good, often better than they really are. Portable phones are marketed as the best thing since sliced bread, but to me they're just another expensive gadget. The way he goes on about her - you'd think she was the greatest thing since sliced bread.

See also: best, bread, great, since, slice, thing