If you want, extremely complex. The LISP Generator utilizes nearly the entire Auto LISP language. There's no limit to how large your programs can be, and no limit to how complex they can be either. Even though most programs can be written in a straightforward or "linear" manner, you have the option to write highly embedded code. You can nest multiple IF and LOOP statements within each other. Also, you can always feed complex operations or math equations as direct input to larger operations, which themselves could be embedded or "nested" in other operations, and so on. So, the sky's the limit.
