I can't really say 'what African-Americans thought' about the film, but I thought you might be interested to read 'what one of the biggest African-American newspapers wrote' about the film. The Associated Negro Press has an article on the premiere that was published [EDIT: sorry, I can't work out how to link to the article, it's on page 8] in the Baltimore Afro American (the year later it had a circulation of 240,000, so fairly influential in terms of black newspapers). The headline is about the fact that the films star, James Baskett, wasn't invited to the event, but there's also some opinion on the film. The author notes that the setting, a Southern plantation, is an 'antiquated locale somewhat obnoxious to the aspirations of a people getting away from slavery time settings', but is a fan of the acting: saying that Baskett 'took possession of Joel Chandler Harris's home spun tales and told them with such delightfulness to the accompaniment of Disney's animations that the previewers of color forgot momentarily the inference of an outmoded dialect and "old south way of life"'. It's certainly positive, despite quite serious reservations. However it should also be fairly obvious in what ways this view would be likely to change in an era when there were black actors in mainstream films that didn't have the same problems.

Behind a paywall, but the Pittsburgh Courier (circulation 280,000, same source as above) doesn't seem to have reviewed the film, just reporting on the fact the the NAACP disapproved of it (link is for anyone who has access, apparently it's a proquest database, so a bunch of libraries probably have access, though mine doesn't seem to).

The New York Times review has the NAACP's statement at the bottom of the page (they incorrectly state that the film takes place before the US civil war, but the NY Times reviewer makes the same mistake).

The movies wikipedia page actually has quite a good selection of opinions from the time, a number of them from African-Americans.