I think that everyone has a different experience with clindamycin phosphate for acne. It did nothing for me but my sister benefited from it. I think it's a hit or miss and one has to try it to see if it works.
I have a friend who saw improvement with clindamycin but couldn't use it for long because of the side effects. The cream gave him diarrhea. The only side effect I had from it was dry skin. So sometimes it works and sometimes it doesn't. And sometimes it works but causes side effects.