What I hate about IK is that I have to also use joint limits to get good results. It seems even the simplest change to a figure's pose results in the unnatural twisting of the wrist, side to side motion of the knees, etc. (Limits are OK, but I find some of the default limits a bit too strict and others not strict enough.) IK would be much more useful if the hands and feet could twist/bend/rotate automatically as they are being translated to prevent unnatural bending.