YOU probably all know the name of the online restaurant reservation service that went public last year and enjoys a market capitalization of well over a billion dollars: OpenTable.

The company’s stellar success has drawn some grumbling in the restaurant industry. Why does OpenTable deserve to prosper while some of its restaurant clients struggle merely to survive?

“Have the ascent of OpenTable and its astronomical market value resulted from delivering $1.5 billion in value to its paying clients, or by cunningly diverting that value from them?” Mark Pastore, the owner of Incanto, a San Francisco restaurant, recently asked in his restaurant’s blog. (With Friday’s close at nearly $72, OpenTable’s market valuation is now over $1.6 billion.)

One naturally feels sympathy for restaurateurs, who must contend daily with hellish business conditions. But Mr. Pastore’s restaurant doesn’t use OpenTable, so he didn’t mention the actual costs of the service. When I obtained the figures from the company, however, I was surprised: they didn’t seem outsize.