I like the CL spec as an early example of a spec for a language that balances performance and dynamism. In the big picture I'd say that it taught people how to write specs for languages like Java, Python, Javascript, etc.

CL was deeply unpopular at the time for quite a few reasons: it really had a 32-bit mindset which made it a bad fit for the machines many people had on their desktops at the time, also the language has enough performance-oriented details that it's not as simple as a LISP can be.