Alright, so Rebel Wilson's Super Fun Nights is plus-sized, what's so funny? Having fun? Rebel Wilson (centre) fails to spark in her new US series. Any time a big, funny woman bursts on to our screens, she's greeted with surprise and delight. She's like a breath of fresh air, a welcome change from the parade of carb-starved and frequently interchangeable actresses that populate the small screen. On the American crime shows, in particular, it's all angular, businesslike brunettes who look like they'd kill for a sandwich. The latest plus-sized funny lady to break through is Australian Rebel Wilson in her American comedy series, Super Fun Night. She joins an estimable troupe of women who stand out because they look different, whether an issue is made of their size on screen or not. Often, they play second fiddles or best friends, like Magda Szubanski in Kath & Kim, Miranda Hart in Call the Midwife or Melissa McCarthy in Gilmore Girls. That kind of casting is also common in movies: think of Rosie O'Donnell in Sleepless in Seattle or A League of Their Own. But on TV, at times, these large-size funny ladies get the chance to be front and centre, like Dawn French in The Vicar of Dibley. Following a breakout supporting role in Bridesmaids, McCarthy went on to star in Mike & Molly, a comedy series about the romance between a couple that meet at Overeaters Anonymous. Possibly the most ground-breaking performer of this talented women's group, however, is Roseanne Barr, who brought her spiky brand of humour to the domestic sitcom. The family in Roseanne was flannel-shirted and blue-collar, and Barr saw herself, rightly, as something of a pioneer in bringing the problems and pre-occupations of their social strata to prime time. She deliberately crafted the show to reflect the lives of people who weren't doctors or lawyers and didn't look like fashion-catalogue models. Her triumph was that, in spite of a famously fractious production process, what emerged added a valuable fresh dimension to TV comedy. Regrettably, on the basis of its muddled and mushy early episodes, the same cannot be said for Super Fun Night (Tuesdays, Nine, 8pm), in which Wilson stars, as well as having an executive producer role. After supporting roles in Bridesmaids and Pitch Perfect, Wilson has become a Hot New Thing in the US. Rightly identified as a distinctive talent, she was quickly handed the keys to the kingdom: her own show. She plays recently promoted corporate lawyer Kimmie Boubier and that's a stretch to start with. Kind but clueless, she appears utterly unconvincing as a lawyer, which is especially ironic, as Wilson has a law degree. Kimmie lives with her BFFs, Helen-Alice (Lisa Lapira) and Marika (Lauren Ash), and, while they're unstintingly supportive of each other, they're apprehensive about socialising in the wider world. So far, the best thing about the show has been the as ever wonderful Kate Jenkinson cutting loose as the skinny bitch who's Kimmie's nemesis at the law firm. Super Fun Night is essentially a soft spin on the Ugly Betty premise: Kimmie's no oil painting, but, wow, she's really nice, if blithely unaware of just how incongruous she is in her workplace. But where Betty initially had wit, vibrant colour and a snappy supporting cast, SFN feels half-baked and messy. It looks like the efforts to mould Wilson and her style of comedy into the shape apparently required for network TV has blunted her appealing edges and what remains is pretty bland. In the local sketch comedy series The Wedge (2006-07), in which she appeared as a writer and performer, and the 2008 SBS comedy series Bogan Pride, which she wrote, produced and starred in, Wilson demonstrated her gift for wrapping her characters' often-icky observations about life and personal hygiene in a disarming sweetness that rendered them both startling and very funny. But here, a saccharine-sweetness smothers everything. Episodes feature clumsy messages: Don't lie on your profile when attempting internet dating; you're only a loser if you don't have a go, blah, blah, blah. The ABC network might have offered Wilson the keys to the kingdom, but it has given her a Barbie dollhouse to decorate, apparently afraid that anything messier might alarm viewers. In doing so, it has robbed her of the spark that made her special. It's a battle that Roseanne fought hard to win. Conan O'Brien, an executive producer on SFN, has said that one of the qualities that initially appealed to him about Wilson was her "willingness to be bold." Unfortunately, there's little evidence of it here.