Returning to the scene of their FA Cup debacle against Leicester City it was a much-improved Forest who gained a vital point in their relegation scrap.
"When we were in on Sunday I said to the players it will be interesting to see how far we have come (since that defeat)," said Cotterill, who praised his side's discipline as 'magnificent'.
"And that was a measure of how far we have come, so we are really pleased."
Opposite number Nigel Pearson had few complaints about the result, acknowledging the strength of the Reds' rearguard.
"In some ways it is two points dropped," he said.
"But they set out to not get beaten and they achieved that so we have to give them a bit of credit for that.
"We tried to win the game but we just didn't have that cutting edge."