I guess most people visiting this forum are already fans, but if you're still in doubt about whether you should see this show: Just go watch it already!
I just finished the final season, and I was continuously blown away. The show just keeps getting better. Great characters, plot, action and drama, while the show also touches on some pretty deep themes and concepts like the nature of humanity, the need for a goal or cause, personal responsibility, government, justice, faith and science, good and evil, and so on. If you'll allow it, you'll be well entertained, deeply moved and thoroughly impressed. It'll leave you wondering about the nature of things. And if that doesn't get you, there's always Tricia Helfer in some pretty skimpy outfits.
So there you have it. You have no excuse. Go buy the DVDs now!