I watch a lot of TV, but Farscape is probably one of my favorite sci-fi series out there. It lasted for four seasons, and a mini-series to end it. So many people liked it so much that they fought for it to get the mini-series.
The series is about an astronaut testing a shuttle that gets sucked into a wormhole, and transported to another galaxy far from earth. He joins a living ship, and becomes part of a crew of aliens. When I first watched the series I didn't know what to expect, but as soon as I started it I couldn't stop until I finished the show.
If you are really into sci-fi I strongly recommend Farscape because the characters are really compelling, and the stories are something I haven't seen before. It hooked me the very first episode, and I think it will do the same for anyone who decides to watch. In the end, my rating is that you should watch this series as soon as you can.