I'd prefer that a LispWorks user answer, but there are quite a few interesting features, such as:

- tree shaking and small binaries (±5MB a GUI app)

- the CAPI cross-platform and native GUI toolkit

- mobile platforme runtime (iOs, Android)

- its Java interface

- its KnowledgeWorks system for "rule-based, object-oriented, logical, functional and database programming"

- more?

ps: today we maintain a list of pretty decent libraries: https://github.com/CodyReichert/awesome-cl/