Great sci-fi show with a very surreal feel to it. Sadly it was cancelled way too early, but that did enhance its sense of mystery. I loved it.
Basically the cast of 5 is out flying some shuttle mission when the earth is destroyed. They get sent back in time 5 years by an alien that tells them to find out what happened so that they may try to prevent it. The scene that follows where they discuss what just happened over coffee in a diner is really great and the show has a lot of moments like that.
Sledge Hammer! is the best Dirty Harry satire out there. And it has spectacular Naked Gun type slapstick. Most underrated show ever.
It got a lot of shit for being so different to other Stargate's and basically killing Atlantis to fund its huge budget but if you like sci-fi you should definitely watch it. It has amazing visuals, soundtrack, Rush is a fantastic character, and season 2 has some of the best sci-fi episodes since The Next Generation. Finding out what Destiny was created for is also super fascinating. I wish it didn't end.