not all it's cracked up to be

It is disappointing, it does not live up to its reputation, as in The restaurant wasn't all it's cracked up to be. This term uses crack up in the sense of “to praise,” which survives only in this expression. [Colloquial; early 1800s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.