I think if we're all honest, the biggest disappointment is that if you take away the two to three times a year he gave a nationally visible speech promoting this or that reason why the US needed to "stay the course in Iraq" (or similar verbiage), George W Bush has been fairly non-existent for the past six years.
I mean, how many times did he wield the veto pen in eight years - once, twice?
And other than the periodic insistence that steady military intervention in Iraq was important, what will historians look back and note as something which GW Bush really got behind and brought into reality?
To that end, I can't see much of a difference between GW Bush and either Carter or Gerald Ford.