It's a giant robot anime from the makers of Neon Genesis Evangelion, although with a very different tone. It's joyful, fun, over the top and almost revelling in shallowness. However it's got a richer, more sophisticated story than you'd expect from any normal series, even had it had twice as many episodes in which to tell it.

The most important thing to know is that we're talking about Gainax. In an industry that in recent years has been shrinking back into what it perceives as safety, i.e. otaku-targeted cute "moe" girls, Gainax loves to burn its bridges. Their anime will be trampling on your preconceptions and will have probably gone so insane by the time they hit the final episode as to satisfy some people's definitions of unwatchable. It's famously a studio of geeks, making what they want to make. Admittedly they'd recently joined the cute girl herd and in addition diluted their brand with the likes of Melody of Oblivion, This Ugly Yet Beautiful World and He Is My Master, but that doesn't mean we've forgotten earlier work like Gunbuster, Nadia: The Secret of Blue Water and of course Evangelion.

When Gainax does a new anime, people pay attention. Futhermore this one was packed with famous voice actors and akin to a mission statement, like a Moore/Morrison retro celebration of the giant robot genre. It's having fun. It's high-energy, brash and in your face. Its heroes' catchphrase is, "Who the hell do you think I am?"

However for those not steeped in the giant robot genre, I think what's special about this show is its story.

In short: it gets big. Really big. Insanely, gloriously, "break Einstein into bite-sized pieces" big. It's worth watching this series just to see how this story builds and builds. Unkillable characters get killed, so that the story can go somewhere new. The story's willingness to bust through all limits will be thought-provoking, then startling, then eventually more absurd than you'd have imagined possible. The finale has galaxies being crunched up like balls of newspaper. In the beginning though, we're merely following two losers who live in tunnels. Mankind lives underground. Kamina (loser #1) is a swaggering loudmouth with the common sense of an ice-cream flamethrower, but also a charming faith in his friends and refusal to countenance the possibility of failure. He's the world's biggest tosser, but he's also entertaining. Meanwhile his best friend is Simon (loser #2), who's timid and only good at digging.

I really liked this initial set-up. It's a claustrophobic dystopia of tiny, inbred communities barely aware of each other's existence. Some have turned in on themselves with weird religions and brutal survival rituals. You could tell an entire series in the world of these tunnels... but then one day a giant robot comes smashing in.

I'll avoid further spoilers and you should too. There's a lot to admire in this storytelling. Best is perhaps what they do with Rossiu, who's a humourless puritan with a stick up his arse and yet gains weight by staying exactly the same but in a different context. Interesting things happen to antagonists. If you're going to try this show, either abandon it immediately or stick with it through to the end. No other option is permitted. If you decide it's getting boring and bail at episode eight or something like that, you're an idiot. You've managed to make it that far, so rest assured that whatever you're assuming is about to be proved wrong and there's cool stuff ahead.

It's also darker than it looks, for something so triumphant. No one has plot immunity. Anyone can die, while the ending (including a "further decades later" section after the credits that took me by surprise) is sombre and autumnal.

However on the downside, the characterisation feels almost defiantly shallow. There are some characters I like in there (Viral, Rossiu, Lordgenome... the bad guys, basically), but an awful lot of the heroes are stupid and know it. They're up for a fight, they're infinitely enthusiastic and they get confused when anyone uses long words. Kamina is like the high king of these people. Simon is more complicated, mind you.

The reason, I think, is paradoxically the scale of the plot. In something like Evangelion, the characters are the plot. They're inseparable. Shinji simply is the story and there's no way of extricating him and still having something that could be called Evangelion. Here though, the logarithmic levels of escalation means that the characters are going to be the puppets of the plot structure rather than the other way around. Admittedly Gainax still do pretty well despite this, with some cool new perspectives after the first time-jump (especially for Rossiu) and the main (surviving) cast all getting big character journeys, but at the end of the day these are twiddles to the side of the plot rather than anything inherent to it. To an extent, the slightly generic characterisation is even deliberate. This is a celebration of its genre, not a deconstruction. It's not trying to be Evangelion 2.

Then there's Yoko. I don't get Yoko. I keep feeling there's something I missed with her character. She loves big guns and I think she's supposed to be badass, but she never seemed to live up to her billing. The most important thing about her is her boobs, but even there Gainax is merely teasing us. They're having a laugh with the fanservice. This isn't a "tits out for the lads" show. The TV studio thought episode six needed a top-to-toe re-edit to be suitable for its broadcast timeslot, but I think that's silly and to be honest even the original version is family-friendly. (Both versions are on the DVD.) Don't get your hopes up. The ogling excess is being played for self-parody.

Oh, and Yoko's voice actress isn't what I'd have expected either. She's almost demure. One fun game you can play with the DVD box set incidentally is to listen in Japanese (a couple of odd decisions, but still my favourite), German (works really well), French (sometimes inappropriate, but occasionally wonderful) or English (my ears, my ravaged ears).

The visual side of things though, I love. They have weird mecha designs, inspired by animals or possibly the heads on Easter Island. Meanwhile the art is playing fast and loose, regularly throwing in extreme styles that you might expect to see in animation tests for laughs, but not in the finished product. They also throw in visual references to Evangelion, Harlock and Space Battleship Yamato, just to name the obvious ones.

Overall, I'd give this half a recommendation. There's some fascinating stuff here and I'm impressed by some of the notes they find, even after going berserk at the end and then pulling it back for surprisingly heartfelt moments. I also really appreciate a series that's stretching our ideas of how much plot development you can fit into this kind of episode count, instead of having the usual flabby period in the middle as a ten-episode story gets padded out to 26. However at the end of the day it's still a gigantic retro homage to a dumb action genre. The first run of episodes in particular to me felt lightweight, although with occasional good (i.e. darker) bits with the subterranean dystopias. There was too much mindless fighting from swaggering macho heroes who didn't know the meaning of "failure". At that stage it was kind of fun, but no more.

In hindsight though, I like it better. Gainax maintains its reputation. From what I hear though, I wouldn't bother with the two compilation movies if I were you.