AoA is an essential tool for accident investigators and frequently thier reports refer to it - and more than one has commented that an AoA guage would be useful for the pilots. If you have the option of displaying the FPV (Flight Path Vector) on the PFD, then you can get a good idea - the difference between your attitude and the FPV is your angle of attack. I have flown military aircraft with AoA guages and it's one of the most useful intruments in the aircraft. I once encountered an ASI failure (common on this type due to pressure changes during manouevring) - the subsequent approach using AoA and power wasn't an issue.
But one thing I noticed in the recent increase in stall training post AF447 is the lack of awareness of pilots regarding the basics. When we did our instrument training and practiced partial panel, we should all have been briefed on the basics - i.e. that flight is an equasion where Attitude = Power + Performace. Take any one element away and we can still deduce it from the other two. For example, If I take the speed indication away, I can still aprroximate the speed to fly by setting attitude against power. At most cruise levels I know that for most weights on the A320, 2.5 degrees nose up and 85% N1 will give me a safe speed. Of course, this has been reinforced in the recent training, but I was suprised at how many of my colleagues had a problem remembering it.