Mad Men is back. Two years ago, this would have caused a great deal of excitement, and attracted a lot of attention. Now, the show's seventh season opened to some of its worst ratings yet. In practically every sense, the series is becoming increasingly irrelevant. After six years, and numerous delays, people seem to have finally grown tired of the show about the sixties advertising agency and its sometime creative director, Don Draper.

Much of this has to do with the changing television landscape in America. When it was first shown, Mad Men was a breath of fresh air. In 2007, the audience knew Tony Soprano so well, James Gandolfini didn't have to say anything – every glance or shrug was a shorthand, a secret language. The Wire's sprawling storytelling, and careful pacing had seemingly exhausted every problem of inner-city Baltimore. The television audience that duly pays its HBO subscription, and prides itself on sophistication, wanted something new, and something different.

Mad Men was that. It felt different. The actors were not just TV-handsome, but looked like they belonged in the Golden Age of Hollywood. It was, and remains, one of the most beautifully shot series ever to air: every symbolic moment, every longing stare captured flawlessly. The sets and costumes in the series, which were the first thing that attracted the attention of audiences (apart from Jon Hamm's chiseled jaw), are perfect to a fault: even the ice cubes are cut the way they were in the sixties. It's a tremendously stylish show, and, unlike the inner-city grime of Baltimore, or the blandness of New Jersey suburbs, the settings look glamorous and alluring.

Much of the excitement has tapered off precisely because that shine can't last forever. If the creator, Matthew Weiner, had his way, the show would probably be over by now, but the thought of losing Breaking Bad and Mad Men within the same year seemed too much for the network executives at AMC, and so the last season was split into two halves, and will finish sometime in 2015. Mad Men has been forced to square off against new competition from rival networks such as HBO, with Game of Thrones and True Detective, whilst Netflix and Amazon Prime have challenged the traditional TV network model. Faster paced shows with a similar sensibility, such as Hannibal or even Justified, do much more to hook and please their audiences. In an age where show runners interact with the viewers, à la Moffat and Gilligan, Mad Men's style feels antiquated, and there is little viral about Matthew Weiner's secrecy (the whole Megan/Sharon Tate conspiracy discounted). A show respected, it is quickly becoming one that few people talk about.

That is a shame, because so far, season seven is fantastic. The accusation that the show is all style and no substance is rather tired, and Don's quest for redemption makes for a fascinating character arc and a very good rebuke to the critics. If Breaking Bad was a race against time, an attempt to really live until your number is up, Mad Men is about the inevitability of time. Don, Peggy and Roger may try and reach out again, and correct their behaviour, but in the end, they will slowly fall into the same self-destructive tendencies and patterns. TV characters learn life-changing lessons all the time: Mad Men shows how, with time, their effect wears off. Much has been made of the fact that the show is nearing the end of the 1960s and the change that signifies, but Matthew Weiner knows better than that. Peggy may be a big time copywriter now, and Joan a partner, but the decision room is mostly closed to both of them. Don nearly destroyed the agency, but he gets to come back – with caveats, but the door is always open to men like him.

There has been some progression for both Don and Peggy this season. As Don's daughter Sally begins to accept her father for who he is, we see Peggy frustrated under the new leadership of the ad agency. Don was terrible to her, but he also pushed her, and appreciated her abilities when it suited him. Whilst the new leadership wants a quick, snappy copy, the true extent of her talents is damned. Both characters have stalled, and been pushed to the fringes, and it is both immensely satisfying and deeply depressing to see them try and worm their way back into the limelight, which they should recognise for the mirage that it is. Meanwhile, Roger, who is experiencing his seventh renaissance, finally has to deal with the fallout of his failures as a father. From a show that was mostly about identity in America, Mad Men has quietly shifted into one about fathers and daughters, both real and imagined.

Mad Men feels like a series close to its end. The show's direction and pacing have become slower, whilst each exchange and glance seems to have adopted increased meaning. It is still an important show, as far as a TV shows can actually be important. Its now old school approach jars with much of what is out there, but also proves that an anti-hero can be compelling without descending into outright villainy, and that a show does not have to be set in a realm, or a prison, to be exciting.

Mad Men is broadcast on Sky Atlantic Wednesdays at 10pm.