The Early Show correspondent Kelly Cobiella says it's an-over-the-top show in which Alley plays herself, a woman at war with food, her weight, and Hollywood.
With self-deprecating humor, she makes jokes about being fat and unemployable in show business.
"She's the fat girl on the outside trying to get back in," notes TV Guide critic Rochelle Thomas, "and that's why people will watch. People identify with her, at least, I identified with her (struggles)."
But, observes Cobiella, Alley is also hitting a nerve.
While plus-size actresses such as Camryn Manheim and Queen Latifah have helped break the Hollywood cookie-cutter ideal, this show, women's groups charge, is a giant step backward.
"A show that seems to be set up to make fun of fat people or to describe how miserable their lives are, is not sending a good message, and it's not the right message," laments National Organization for Women president Kim Gandy.
Alley's 200-plus pound character is clearly unhappy about her weight, and not everyone finds that amusing.
"If the idea is that fat equals desperate," says Gandy, "then that's not going to be good for any of us, and certainly not for people who are overweight, healthy or not."
"Some people will be really turned off by this subject matter," points out Jess Cagle, People magazine senior editor and a frequent contributor to The Early Show.
Once a sitcom sex symbol, Alley has been trailed by the tabloids for years, with every added pound seemingly registered in humiliating headlines, Cobiella says.
"There may be people who are heavy themselves and they don't think it's a laughing matter, (and people who aren't heavy and still don't think it's a laughing matter)," Cagle continues. "I think it's a very touchy subject for a lot of people."
"Is obesity a taboo subject when it comes to comedy?" Cobiella asked Cagle.
"People make fun of fat people all the time," he responded. "What Kirstie Alley is doing that is so great is, she's taking back the night. She's the one making jokes about it. "
And, Cobiella says, pointing to the double standard that has prevailed in Hollywood for years.
"Why should I have to lose weight to get this job?" Thomas paraphrased Alley's character. "John Goodman didn't. Jason Alexander didn't."
"And I agree with her," Thomas adds.
Yet other critics say the whole premise of the show is pretty thin.
"I don't think she's making sport of fat people. I think she's making sport of herself. And maybe that's one of the problems with the show -- she's not that interesting," chides Los Angeles Times TV critic Paul Brownfield.
In the end, Alley could have the last laugh, Cobiella notes. At 54, she might be a fat actress, but if people tune in, she'll be worth her weight in gold.
In real life, Alley is actually trying to lose weight, and is a spokesperson for a major commercial diet company.
"Fat Actress" appears on Showtime, which is owned by Viacom, as is CBSNews.com.