what I remember about epic 4:
Broken skills
Imbalanced skills
Mana problems for DM, Healers
crapy damage for dark magicians some DM started to use Dirks instead of staff for faster ks
HLP partys started to pop up which caused lots of noobs
I quit rappelz at epic 4 and came back few epics later
ask anyone who actually played epic 3 and later and my words will be proved