My biggest frustration with the Cleric is that both of the best offensive skills, (Arbenos' Might and Sacred Fire) deal fire damage. It makes taking down a red dragon far more difficult than with the other classes. It would be nice to see another temple (the other classes have two guild houses with additional advanced skills) that teaches more offensive skills that deal at least one other type of damage.
On a related topic - when playing either the warrior or the rogue, Hirge is by far my favorite companion (I haven't seen much love for her on this forum, but I find her ability to Heal indispensable, especially if I am trying to run dungeons for gold/xp without spending money on healing potions). I just wish that, when fighting the previously mentioned red dragons, there was an option to tell her NOT to heal it using Arbenos' Might. I also wish that we could instruct companions to avoid damaging situations - just because an Ancient Mummy attacks you does not mean that you have to sit in its poison gas cloud attacking it...
Just nit-picking here - great game!