Very good series, I really enjoyed it, but you must be warned of some of the sexual and languid parts of the series. THere is drinking, there ARE sex scenes (less and less as the series progresses; cylon Number Sixes are frequently involved) and there IS quite a bit of language, though the F-bomb is replaced by 'Frak' (yes, it's spelled that way, look it up at BSG wiki). There is some 'skin', but there are no parts displayed.
Now, onto the good.
First of all: this is the most realistic SciFi series ever.
It deals with real-world dilemmas such as sex, pregnancy, abortion, violence, genocide, and certain interrogation techniques really make you question the military's methods. It really makes you THINK; does humanity really deserve to survive?
The most questionable characters include Number Six (though she later becomes more of a 'good guy'), Gaius Baltar (basically will do ANYTHING to have sex with ANYONE), and Lt. Kara 'Starbuck' Thrace (though she has her darker sides, she is an inherently good character).
The most morally-just characters include William Adama, Laura Roslin, Billy Keikeiya, Cally, and perhaps the Number Eights and Number Twos, perhaps, later on in the series, Number Sixes.
While I would not recommend this for anyone under 14 (even some who are that age, make sure they're mature), the story is an incredible story (some parts are heartbreaking and heartwarming) that truthfully portrays both the horrible flaws and incredible selflessness of humanity.