The question is subjective, however I do agree with the fact that Lee's portrayal is
clearly insensitive. In this article in LA Times, even the artist's own daughter has said that the depiction was "disrespectful" and "a mockery". Furthermore, in another LA Times article, his former training partner has said that "I feel like [Tarantino] turned [Lee's] confidence into arrogance and his intelligence into mockery". So both of them had very similar opinions about the film.
These 2 opinions come from people who knew the artist very well, and Lee's daughter made it clear that her father's film character is in fact not a character, but a "caricature".
In the same LA Times article, it is also pointed the fact that the film character was very different from the real person - "It stayed so far from the truth of who he was and of any actual encounter he had...It was terrible to watch".
I personally find the line from the film "My hands are registered lethal weapons" to be especially arrogant. The film in my opinion clearly fails to detail the profoundness of the real actor, making him only a pugnacious character/caricature in the film. I don't know if it was Tarantino's intention to make him look that why, but I do think he made a mistake in the realization of the film. He was way too focused on the chronotope (the artistic space-time of the film) and he definitely failed to capture the essence of that era's real artists.