I'd say it's fairly awful!
I play normally duo'ing as a GLD or PLD usually without another healer and sometimes that 'Cure' HAS to be cast NOW!
As I use a controller I'll click the Cure icon (expecting it to work as it should) then I'm immediately off navigating the action bar looking for my next skill, fully expecting the spell to work.

If that click of the Cure doesn't go off (as it hasn't been lately) it often results in rage/death.

(yes I'm aware I should be using macros, thx)