You get to kill people if they aren't compliant, and kill them if they ARE complaint... and weaker than you.
Best of all, I've noticed that being evil really pays off in the long run. Random battles with Cowled Enforcers gives you real battle experience against all the pesky liches and mages you're going to be going up against in latter quests. Also, you can collect some really useful and valuable scrolls. The guards and knights that accompany them usually have some really nice, really valuable armor. Offsetting inflated low-rep-induced prices. If you're patient all those battles will really boost up your level as well. Then again, you’ll be having too much fun to notice how many days you’ll be spending steeped in blood killing peasants. Not like time in a non-linear game matter much anyways. (Who cares if your soul has been sucked out of your body?! That fat woman looked at you funny! Slashy-slashy!)
Remember all you naughty little serial killers; keep your rep at least in the 3-5 ranges. It will keep your neutral party members only slightly pissed, and your evil ones really happy. Pay attention to your rep and you should have little problem using mass murder for fun, profit, and power!
(Additional hint: There is nothing wrong with 'playing good' once and awhile for a really nice item or oodles of gold and EXP. Just murder the agencies that you performed the good for at a later date thus bringing malicious balance. An example would be slaughtering the entire Elven camp, and Radiant Heart after you kill Bohdi and the way to the Tree Of Life is opened up... Again, be patient, those moronic bleeding hearts will get theirs… AT THE END OF YOUR BLADE! AH-HA-HA-HA-HA-HA-HA-HA!)