I'm less interested in questions like "how much credit do the original designers of CL deserve?" and more interested in "what languages should I consider for my new project?". Is Dylan a viable option? If not, why not? "It's not because it inherits common lisp's non-interoperability" is then an interesting point.
Yeah, but that would be bullshit to assume. I use for example LispWorks (commercial, proprietary) and Clozure CL (free, open source) on my Mac. Both have excellent interoperability with C and Unix. Both have a native Cocoa interface to the Mac.