After doneness to the point the meat is tender and pulls cleanly from the bone, there is, in order:
"Falling off the bone" - Self-explanatory. Considered overdone by some, perfect by others.
"Fell off the bone" - Usually seen in ribs kept overly long in foil.
"Dry and tough" - Usually cooked without foiling, long past the point of tenderness, at too low a temperature.