I find many of the interactive features to be over-engineered and/or under-documented. I've never been able to use the condition system to do anything useful. It's not apparent what compiler errors are recoverable and how to recover from them.

I dislike its package management. But this is a general criticism of most languages -- no matter how late-bound the language, there's a consistent temptation toward early binding for performance reasons (see the latter half of http://arclanguage.org/item?id=15587, ie footnote 1. Also http://arclanguage.org/item?id=12057)

Bottomline: while lispers like to say the world hasn't fully understood the power of 70's lisp, it's equally true that Common Lisp is stuck in the 70's and hasn't benefited from ergonomic advances of the past 20 years. It still uses UPPERCASE. These issues are certainly minor compared to having macros. But they carry some weight.