Although this is a teenage show, it's really well done and enjoyable for all ages of sci-fi fans. The story lines are interesting and the characters better developed than in Season 1. Unfortunately, most of the kids became promiscuous this year. I often wondered, "Where are their parents?"
Like all the best science fiction its character and story line driven. At the end of the first season I was very curious to see where the writers would go in the second season. The second season is very interesting. The kids spend a lot less time in High School. It's also more action packed than the first season. The love story and character development seems to take a bit of a back seat to the action, though. Some new characters are added and subtracted which keeps things fresh.
The writing is not top notch. Frequently characters act out of character. Sometimes it's necessary as a plot device but I think sometimes it's just sloppy writing. At the end of the last disc there is a bonus feature when Shiri and Majandra talk about the series and they talk about their character's motivation.
I've just added the third season to my queue.