"He kept his word in all the deals we made," Clinton told CNN at the Clinton Global Initiative annual meeting Wednesday in New York.
He added, however, the United States will "just have to see what happens" with a Russian-led plan to strip Syria of its chemical weapons.
"You work for the best and prepare for the worst in this business. But I think it would be a terrible mistake not to take advantage of the opportunity. And, you know, look, Mr. Putin is very smart." He described their relationship as "brutally blunt."
President Barack Obama in his speech Tuesday at the U.N. General Assembly called for the Security Council to produce a "strong" resolution to "verify that the Assad regime is keeping its commitments."
U.N. weapons inspectors were in Syria Wednesday to investigate additional allegations of chemical weapons use. The United Nations already has confirmed a sarin gas attack in suburban Damascus Aug. 21.
Clinton also told CNN he believes his daughter, Chelsea, would be a better president than his wife, Hillary, "over the long run."
"Day after tomorrow, my wife because she's had more experience. Over the long run, Chelsea. She knows more than we do about everything," Clinton said. "I feel like I'm going to school every day when we have conversations."
Hillary Clinton served as Obama's secretary of state from 2009 to 2013 and was a U.S. senator from New York from 2001 to 2009.