thansk for the explanation on the differences.
As to why I feel its bad its perhaps my playstyle I suppose. I dont use these kinds of spells, as a mage your Hp are so low at lower level when you get hit their going to do far more damage to to me than I can do to them with a spell like this up and running. The damage it does is only a fringe benefit. I would only use this strictly for the AC buff, thats why I said its the only feature I liked. I dont want to get hit.
Spells like mage armor, shield, ghostly visage are my prefered. sure some features dont stack but these buffs last 1 turn / level, while others have 1 round/ level I just though it strange this had the description of 1 hour duration and never though about the conversion.
Suggested fix: since duration is not level dependent and to eliminate confusion state duration = 20 rounds (see reply#4)
damage description would stay the same, which is level dependent