Is Barack Obama 'incompetent'?

I read that:

'Bill Clinton thought so little of President Obama — mocking him as an “amateur” — that he pressed his wife last summer to quit her job as secretary of state and challenge him in the primaries, a new book claims,
……
The title of [Ed] Klein’s explosive, unauthorized bio of Obama, “The Amateur” (Regnery Publishing), was taken directly from Bill Clinton’s bombshell criticism of the president, the author said.

“Barack Obama,” Bill Clinton said, according to book excerpts, “is an amateur.”

The withering criticism is incredible, given the fact that Bill Clinton is actively campaigning for Obama’s re-election.

But according to the book, Bill Clinton unloaded on Obama and pressed Hillary to run against her boss during a gathering in the ex-president’s home office in Chappaqua last August that included longtime friends, Klein said.

“The economy’s a mess, it’s dead flat. America has lost its Triple-A rating . . . You know better than Obama does,” Bill said.
……
Obama, Bill Clinton said, “doesn’t know how to be president” and is “incompetent.”'

I believe that Bill Clinton is disputing that he ever said what he is quoted as having said. Odd, it would be one of the few times he's been so on target for years.