I heard some people complain that APSL 2.0 ( http://www.opensource.apple.com/license/apsl/ ) has too many limitations. What's the limitation of it compared to BSD or MIT?
Unlike the BSD or MIT license it requires changes to be released, so it is more like the GPL or LGPL. However, unlike the GPL or LGPL only the modified file needs to be released, rather than entire program or library.
It is not recommend since it is no GPL compatible.