Here's a problem I have with the user interface. Let's say I want to add a skill to my bar, let's go with stoneskin. Well what exactly does it do? I know it blocks damage by use but how much damage does it block? How long does it last? You don't get a lot of info on the skill pop-up.
Or let's say I want to use a weapon skill. Circle slash perhaps. How much damage does that sucker do? How much more will it do if the mob isn't targeting me? Again, you don't really get a lot of info.
Or take cure. It now costs 45mp. But how much healing do I get for 45mp?
I really think that the skills in this game should give you a more tangible idea of what they really do. For example if circle slash does +200% of your auto attack on a normal hit and +300% of your AA on a hit where you aren't being targeted, it should say so. If stoneskin only blocks 200 hp worth of damage, it should say so.