BOSTON (CBS) – I have to admit, yesterday may be the only time I’ve ever watched an Oprah Winfrey show in its entirety. Late afternoon is a tough time for me to do that.

Listen to Jon’s commentary:

But I have seen enough of Oprah’s act over the years to develop an appreciation of her incredible talent. Her intelligence and speaking skills have always been apparent.

She is an exceptionally good interviewer, asking the right questions with the right tone at the right time. And she comes across as natural, real, and down-to-earth, no small feat for a mega-star in a highly-produced format who has become one of the richest, most accomplished business executives in the world.

Watch Jon’s WBZ-TV report:

And there’s another very commendable thing about Oprah — her altruism. Her philanthropy and use of her clout to help others is extraordinary.

Oprah is a giant in her time, no doubt about it.

But that does not mean that her impact as a cultural phenomenon is beyond skepticism.

She has many critics in the medical field who disapprove of her championing dubious scientific claims about autism and hormone therapy.

Her popular book club made instant bestsellers out of every book she chose, but she didn’t always choose wisely.

And if you believe that our culture has become dangerously narcissistic, with far too much emphasis on self-esteem and self-aggrandizement, you can look to Oprah’s relentless advocacy of feel-good philosophy as a source of the problem.

In the hands of a brilliant creative mind, television can be a powerful social force for good.

Oprah’s legions of admirers are testimony to her brilliance.

But power can be abused by the imperfect, however inadvertently. And perfection is perhaps the only thing even Oprah can’t do.

You can listen to Keller At Large on WBZ News Radio every weekday at 7:55 a.m. and 12:25 p.m. You can also watch Jon on WBZ-TV News.