Changes on "Today" have also smoothed out some of the more interesting quirks, making the new format seem even longer than four hours. Ms. Vieira, who replaced Katie Couric more than a year ago, is pleasant but bland, and not forceful enough to dim the ascendance of Ms. Curry, who was passed over for the top co-host job but seems determined to play the role anyway.
And Ms. Curry has proved that she can cover any subject, from Darfur to diaper rash, without critical distance. (She once led a segment on the power of female friendship by asserting that there is "a lot" of medical evidence that not having long-term friends is "as risky to your health as obesity, as smoking.")
The fourth hour of "Today" feels less like an extension of the three-hour show than a cozy Tupperware party that never ends.