Being a long time trek fan, I can tell you as far back as the 70s Mr. Leonard had a great reputation with the fans. Say his name to any old time TOS fan and you can hear the sense of owe in their voice when they talk about him.
He brought about a sense of class and dignity that the writers built the entire Vulcan culture upon.
To my knowledge he was well respected by cast and crew of both TOS and TNG. I never heard a bad word about the guy.