ABSOLUTELY he was.
His assist record is one of the most astounding records in sports. Considering no PG might never average well above 10 apg because of how the game is changing (supposed better defense

, and NO jump shooters...) that's right up there with the records that will NEVER, EVER be broken.
He did everything you could ask from a true PG, the kind everyone wanted to have on their team. He obviously set up his teammates brilliantly, he hustled, he played D (btw, who's the #1 all time steals leader) and he did the little things (got to the FT line, drew little fouls, made clutch shots).
I never really saw him in his true prime, but from what I hear he was a great player. I can't really comment on being the best player in the league at any time, but I can say that he's probably one of the greatesty players of all time.