I've been looking at parses and decided that I can do more damage.  I knew my spec was good for raiding, but not the best and my gear has reached a point where I can do better with affliction since it scales better with gear than the other raiding builds.  Experiments on the target dummies suggest that I can get an increase of 500-1000 dps.

Affliction builds are harder to play.  There are 6 dots and you have to keep them all up while tossing Shadowbolt or Drain Soul as filler.  Few classes have to juggle like that.

I found a fantastic guide for raiding warlocks at <http://wowmb.net/forums/f106/31741-warlock_raiding_guide_wrath_lich_king/>.  Take a look, it'd be nice if every class had a guide written like that one.