Judd Apatow is such a ubiquitous name in comedy these days that it’s easy to forget what a Johnny-come-lately he is. Aside from a couple of one-offs in the mid ‘90s, he’s only been in the business of making movies since 2004. And his directing career surprisingly consists of just four films.

All of which is to say that even though his star has risen pretty quickly, he has yet to prove that he can be counted on time and again to put out a quality product. Case in point: This Is 40, on which he is the triple threat of writer, director and producer. The film follows two supporting characters from Knocked Up, Pete (Paul Rudd) and Debbie (Leslie Mann), as they deal with the fact that both of them are turning 40 at the same time.

The film explores a lot of the issues that come with being at that point in life, such as the effects of age on the body, how to be a good parent, trying to work your way out of poor financial decisions and dealing with your own parents. The film has no set plot or framework; it’s essentially just a series of vignettes set loosely around the week both Pete and Debbie celebrate their birthdays.

Therein lies Apatow’s first mistake. By not giving the audience any kind of true reference point, it feels like the film is just drifting from place to place. When it’s funny, it’s really funny, but because the film jumps around so much, it never develops any kind of rhythm.

The second mistake is one that Apatow repeats from his last directorial effort, Funny People. Much of This Is 40 is dramatic rather than comedic. There’s nothing inherently wrong with mixing drama with comedy, but the balance is tenuous and needs to have a steady hand to maintain it.

Unfortunately, Apatow’s balance is out of whack, and so what could be interesting turns of events usually come off as plain depressing. And once you go down the Debbie Downer road, it makes it that much harder to revive any wackiness you want to portray. Characters may be able to forgive and forget, but it’s much harder for audiences to do so in just 134 minutes.

And that’s the final mistake for Apatow: The film is in desperate need of better editors. It's about 30-40 minutes too long. There are many elements, especially those dealing with the fathers of both Pete and Debbie, which could be excised. Albert Brooks and John Lithgow, who play the respective dads, are fine actors, but their storylines are far from exciting and are often confusing.

Rudd and Mann are two of Apatow’s staples, and their interplay is what keeps the movie going in spite of its faults. The film not only stars Mann, Apatow’s wife, but also heavily features his two daughters, Maude and Iris. Cries of nepotism quickly become moot, though, as their interaction is among the most believable in the whole film, for obvious reasons.

As is usually the case in Apatow films, it’s the supporting characters that come off the best. Jason Segel reprises his Knocked Up role with fantastic results. Megan Fox is on a bit of a comedic roll following last year’s Friends with Kids; if she keeps it up, we may just forgive her Transformers transgressions. Other familiar faces like Michael Ian Black, Chris O’Dowd, Lena Dunham and especially Melissa McCarthy make for amusing diversions.

Ultimately, though, Apatow’s mistakes drag This Is 40 down. The film is a slog to get through, both in terms of tone and sheer length. If this is 40, I want no part of it.