This is a spinoff of the series Stargate: SG1. Ripoff would be a more accurate term - and I'm a fan of both, let it be said. The producers did try a little bit to shuffle around the characteristics of the team as a whole - they made the alien a woman, for instance. There was only one brilliant scientist, and he was a geek. They kept the leader absolutely the same - a loner, pretends to be dumb, wisecracking, heart of gold.

There was one crucial mistake in the mix, however - the token black guy - I'm pretty sure they thought he was too bland, and couldn't think up many stories for him throughout the first season. I can see the reasoning for creating a character like that, a sort of Everyman, through whose eyes the journey could be seen, but with such strong characters around, no one was really going to be interested in that. So the character was written out, after a lifechanging encounter with the resident bad guys, the Wraith (an overdose of the toxin they use to strengthen their prey enough to feed on them changed him into a deranged psychopath, basically) to become a recurring character, for the second season at any rate.

The replacement character was much more closely based on the original, Teal'c, of Stargate SG1, with a few wrinkles - he was very anti Our Heroes at first, and much more impulsive. However, he was as tall, younger and even more goodlooking, as well as being a hands on fighter, so he was soon a popular character with the fanbase.

So the team was Colonel John Shepherd, anti-authoritarian with a heart of gold; Doctor Rodney McKay, brilliant physicist, misanthropist and coward, who soon shows that he only talks the talk of cowardice, he's actually as brave as Shepherd; Teyla, the beautiful warrior woman who can connect to the Wraith telepathically, and is suspect at first for exactly that reason. And Ronon Dex, the alien newcomer who arrives in Season Two, tall, dreadlocked, magnificent warrior, fantastically goodlooking.

The heart of the show seems to be the relationship between Shepherd and McKay, banter and derring-do in the face of the lifesucking aliens called The Wraith. But this time, because there isn't one big TV star to unbalance the mix, the other two team members, Teyla and Ronon, are also given a few episodes to show their comradeship.

There are two subsidiary members in the mix - the base commander, Elizabeth Weir, and the doctor, Carson Beckett, but both of these were written out around the middle of the show's run. The producers continually tweaked the show's cast - in the fourth season, the base was run by an import from SG1, Amanda Tapping, which seemed to me to be an outright failure, and in the fifth season by another import from SG1, Robert Picardo, who was much more successful because his character, strangely enough, was always better developed than Amanda Tapping's Colonel Carter. Sad, but true.

So, what do I like about Atlantis? I like the humour - again, because there isn't the big TV star in the way, the level and type of humour is usually much more appropriate to the type of story.

Unusually for me, I like the big strong warrior guy as much as I like the rest of the team - the warrior stuff Stargate insists on usually bores me rigid, they persist in thinking of their target audience as 12 year old boys, but Ronon has a way with him that goes well beyond the norm. They gave him a few subtle storylines too - competing with the geeky brilliance of Dr McKay to be the love interest of the new doctor, played by Jewel Staite, for instance, in Season Five, and competing with Teal'c to be the strong guy in a crossover story in Season Four.

I absolutely adore the interplay between McKay and Shepherd, and I liked it even more when they brought in the real life sister of the actor who plays McKay to be the character's sister, an equally brilliant physicist who chose to raise a family.

It was also a clever move to come across a few Wraith every now and again who could communicate beyond hissing and life-force-sucking - the plot wrinkles that that produces have been a lot of fun. Todd, and Michael, have added a great deal to the mix.

Atlantis lasted five seasons, pretty good going for a spin-off, and it really did go out on a high - the next to last episode was a homage to almost every recurring character they'd ever had, set in an alternate universe where the characters were mixed up in very different ways, which must have been a real joy for the actors to work on. And the last episode took the denouement of the previous one and wound the tension to an all-time high, bringing Atlantis to this galaxy and landing it just off the coast of California.

The final, blissful moment of this final episode shows our heroes looking at San Francisco - and for the fans, this is wonderful, because of course Starfleet Academy will be in San Francisco - and that kind of reference is constant in Stargate. The producers take pride in the way their shows are set in the present day, and in the present day everyone has heard of Star Trek. So there are many injokes and references to Star Trek throughout the show, and it ends with one of them too.

It's a great show. It's a lot of fun, it doesn't take itself too seriously, and yet, like all science fiction, it explores some real issues about our present day world - how do we cooperate with one another? What is worth fighting for? Who do we need to fight? What are our values? If we betray our values how are we different from the people we cast as the enemy? These are issues worth thinking about.