Where did you read that? Everything I've read about the Panter says it was a great tank once they'd ironed out the intital problems and the only reason the PzIV was kept in production was to make up the numbers.

From late 1942 to 1945 some 6000 Panthers were built (less then 3 years) where as just under 9000 PzIV's were built from 1937 to 1945. Panther production is even more remarkable when you consider the fact that the factories were under constant bombing.