On the surface, I actually don't mind this concept. I've said myself I would like to see just a personal "report card" pop up at the end of an instance. Nothing big and detailed, and no real rewards tied to it at all, just something that says "You got an A+ for DPS but a C for Damage Taken. You could really work on avoiding more enemy attacks." The problem is, of course, how to actually implement this without it just ending up being a giant pile of extra work on the developers, and with it somehow being equally applicable for Tanks and Healers.

At the end of the day, I guess I just settle on wishing the game itself was more proactive in giving direction and teaching instead of foisting it all off on the players.