Rugby has become my second favorite sport to watch, behind only college basketball.
I often compare it to NFL football, and rugby is just better. Especially in that it is a continuous action sport. In NFL the average play takes 4 seconds. Then there's about 30 seconds of no action as the teams huddle up, call the next play, go to formation, change formation, and finally hike the ball. In rugby there's a tackle, and the ball is immediately put back into play. It's faster too. An NFL game that has 60 minutes of game clock takes 3+ hours to complete. A rugby match with 80 minutes of game clock is done in under 2 hours.
All players must be able to tackle properly (with no pads or helmets) , carry the ball, pass, and play both offense and defense. It's a great game.