If you have this high minded impression that the New Yorker is some sophisticated analyst of   world opinion, only read by an educated elite. then the cartoon was proper and in good taste and Donuel is not out of line, and completely missing the point, for calling people who don't agree with him "linear".

On the other hand, if you think that The New Yorker is a commercial magazine on news stands across the country and if you realize that the purpose of a magazine cover is to sell magazines and if you realize that a lot of people with buy that particular issue because it reinforces everything that they believe and want to believe about Obama because they are racist or because the are so partisan that they do not think straight, then you may find it tasteless and offensive.

As folks here have pointed out, satire needs to make a point, an accumulation of negative stereotypes is just and only that and can cut both ways. The New Yorker clearly made a business decision not to make a clear statement so that they could sell magazines to Obama supporters and Obama haters.