It's told from the point of view of each character, so the camera of always at the level of their head and you see what they see, hear what they say and even better, hear what they think. It's a bit strange to get used to it, but after a while you can't imagine the show done any other way, and its what makes the show unique.
In a nutshell, it's about 2 guys who live together and are very different to each other. One dry and cynical, the other witless and niave. The contrast and the clash is what makes it entertaining to watch their misadventures and escapades.
Series 1 - 6 is available on DVD and it's worth checking out. Each season is roughly about 6 episodes of about 25 minutes each. Yes, you'd go through them quickly, and probably want to watch them in one sitting! Highly recommended.