Pride and prejudice: 'The New Normal' puts a relationship between two gay men centre stage

Few things in television are as standard as sitcom relationships. Television is awash with girls pining for guys, single ladies looking for love, treatises in male bonding and female friendship. Yet what all these relationships have in common is that they're overwhelmingly straight.

Gay characters will make the odd appearance in supporting roles certainly – and in the case of Happy Endings' slovenly, depressive Max may even break free of the "flamboyant" gay stereotype – but even then with a few notable exceptions (Modern Family's Eric and Cameron, Glee's Blaine and Kurt) their love lives are rarely allowed to take centre stage. That changed this season with the arrival of two sitcoms that placed gay relationships in the spotlight.

Partners, created by the team behind Will & Grace, was the more traditional of the two, essentially an updated Will & Grace with the twist that it's now about a gay man and his straight business partner/best friend. The gay man was pretty much a 2012 version of Will & Grace's Jack and the show felt a little as though it fell through a wormhole from the 1990s. Affable without being interesting, it failed to find much of an audience and was cancelled by CBS in November.

The New Normal, which has been picked up for the whole season and will air tonight on E4, is altogether more complicated affair. Before it started this comedy about a gay couple having a baby through a surrogate was already one of the most talked about new shows of the season. A television network in Utah refused to air it, right-wing pressure group One Million Moms called for a boycott and one of the show's stars, Ellen Barkin, took to Twitter to mount a vigorous defence of it.

For while The New Normal might not be the first comedy to look at gay marriage and parenthood – Modern Family has tackled similar issues throughout its run – it is the first sitcom where the central pairing is between two gay men with the rest of the cast in supporting roles.

So far so ground-breaking, however, the problem with The New Normal is the very thing that makes it so different in feel: it's a Ryan Murphy show.

Murphy, the man behind Popular, Glee, American Horror Story and Nip/Tuck, can be a strong writer. His shows exist in a candy-coloured larger-than-life world where the most outrageous actions are made ordinary and anything can and does go. When it comes together as in the earliest episodes of Nip/Tuck or Glee then Murphy's world is a pretty entertaining place to be.

The problem is that alongside that Ryan Murphy, the writer with a keen eye for the brilliantly bizarre, exists the Ryan Murphy who enjoys poking viewers with a sharp stick and then retreating to snigger behind his hand.

That Murphy is at the forefront of The New Normal, ensuring that while there are some good moments (most notably the genuine warmth at the heart of Andrew Rannells' and Justin Bartha's relationship and the fact that that relationship is clearly sexual, rare in depictions of gay couples on US television), there are many more where the entire enterprise threatens to spin off the tracks faster than you can shout "this makes absolutely no sense whatsoever…"

For a start there's the problem with tone. Murphy seems unsure whether he wants to preach to his audience – the pilot episode alone contains enough teachable moments to leave the cast of Glee groping for the right sappy song – or whether he wants to sit back and send the whole thing up. Frequently, he decides to do both in the same scene. Thus, Bryan's desire to have a baby is initially expressed in entirely shallow terms ["I want us to have baby clothes – and a baby to wear them."] but five minutes later and we're expected to believe this tin man has both a heart and soul. It's a credit to Rannells, a stage actor best known for The Book of Mormon, that he almost manages to charm us anyway.

The biggest problem, however, lies with Barkin's role as the surrogate mother's bigoted grandmother. While Barkin delivers a fully committed performance, the character is a typical Murphy trope: the person who says the forthright, cruel and often crude stuff you don't want to hear but can't quite help laughing at aka the Jane Lynch role.

For the first few episodes of Glee at least, Lynch's red track-suited Sue Sylvester was pretty funny, by contrast Barkin's Nana isn't so much entertaining as odious. She dubs Rannells and Bartha "salami smokers" refers to a lesbian couple as "ugly guys" and thanks an Asian woman with the line "You people are so darn good at computers. And thanks for building the railroads." It's Murphy at his most gleefully childish, playing it broad and crude and hiding behind the idea he can't possibly be being offensive when his show is a primetime sitcom with a gay couple at its centre. As Salon's review caustically remarked about this "We're just being honest" defence: "honesty doesn't make hate OK."

And while the sitcom pulled in a respectable 6.9 million viewers on its debut and has continued to draw solid ratings of around five to six million, early reviews were mixed. The New York Times hailed the sitcom's "wit and charm" but concluded the Barkin scenes sounded a "rare false note". The Washington Post, on the other hand, loved Barkin hailing her as "a cruel hybrid of conservative activist Phyllis Schlafly and Absolutely Fabulous's Patsy Stone (with Callista Gingrich's hairdo)" while Variety admitted "there's much to like… along with warning flags as to where the series could easily skid into the Pacific Ocean."

That last point may ultimately prove to be The New Normal's undoing. For unless Ryan Murphy decides which sitcom he's making: a perky ode to blended families with a strongly sentimental streak or a jet-black send-up of family values that aims to unsettle as much as amuse, then The New Normal will never be more than the sum of its disparate parts.

'The New Normal' starts tonight at 9pm on E4