I've been talking a lot lately about how so few movies are made for movie screens and cinemas. Anchorman 2: The Legend Continues is the opposite, working only under very specific conditions (and a movie screen isn't one of them).

The first is probably a DVD viewing, surrounded by pizza and beer and a group of friends who love it as much as you do, but knowing and loving the whole Anchorman mythology is definitely the second one. I saw this film with someone who'd done neither and tittered at a couple of jokes but didn't like it overall, something that made me understand how Anchorman is all about your perspective.

What it makes you realise is how ill-defined the characters are if you come to them cold. Is Ron Burgundy (Ferrell) an idiot and a buffoon more interested in his hair than anything else, or a comic genius because of his many quips ('Tony Danza's scrotum!', 'By the hymen of Olivia Newton-John!')? Is Brick Tamland (Carell) mentally ill, or supposed to be merely child-like.

The story hardly matters. More so than many other comedies with no plot, it's merely a timeline to hang the characterisations and lines on. Ron again finds himself down and out, introducing Seaworld acts and miserably telling the audience how he's so lonely he paid a homeless guy to spoon with him.

But he gets a shot at a big time bigger than he's ever imagined in the form of an offer to work in New York at the first ever 24-hour news service, run by an Australian industrialist. Once there he makes enemies with the solver-tongued alpha male of the industry (Marsden), receives the amourous and terrifying attentions of his very forward African-American producer (Good), hits rock bottom and loses his friends again and has to claw his way back to the top.

There's actually a single smart moral in the movie about how media companies in the 1990s invented news to fill the airtime of 24-hour news channels when most of the crap they talk about isn't news at all. But it's the only idea of note – the rest of what goes one can be described by talking about the news crew battle that takes place in Central Park when Ron is rushing to be with his family.

Where the comic motif of the fight from the first movie starred a couple of cameos from the Ferrell/Vaughan/Wilson/Apatow/McKay fraternity, here it's the m.o. of the whole 'bigger, better, more' notion of a sequel as Sacha Baron Cohen, Jim Carrey, Marion Cottillard, Will Smith, John C Reilly, Amy Poehler, Tina Fey, Liam Neeson and even Kanye West show up as news crews from all over the world, weapons in hand.

There's an extended sequence of Ron suffering temporary blindness in which he and his family nurse an injured shark back to health (if you know what Anchorman's all about, you know you don't have to ask) that feels like padding, and if you sat down and sketched out the story, most of what goes on would probably feel similar.

But it's absolutely about the gags rather than the story. It's just that after the original has fomented for so long in our culture and become as classic as the early movies by the Zuckers or the early work of Monty Python, it's kind of surprising that the sequel isn't comic writing par excellence but just another silly movie with a few jokes.