It's addictive. It's insane fun! It's completly different than riding MX.
After the first little ride on a friends bike I was totally hooked, I
HAD to get involved there was no other choice. See that near vertical hill? Your Spiderman. On MX you lay the bike over and put your leg out to help rail a turn on a trials bike you try to keep your shoulders square over the bike, feet on the pegs and let the bike fall under you while countering by moving your hips to the outside. Off road or MX you try to pick a 6" area for your front tire, trials you try to pick the same pebble.
I think it's goig to get very popular in North America over the next 5 years. It's an riding sport where you don't need 50 acres for a track, the bikes are very quiet and folks generally tend not to get as damaged in a crash. Will I give up my full sized off road bike? Nope! I look at it as just icing on the cake.
Click this for a good trials specific site.