If you use only structs, lists, numbers and strings, print is perfect. It supports circular structure when PRINT-CIRCLE is true.

For custom classes you have to define custom printing methods, because, well, how you print a particular object readably has no general answer: for example, for some data (streams, threads), it makes no sense to serialize them. Java has the "transient" keyword to avoid serializing some fields in classes. You should also set PRINT-READABLY to T so that you have an error if an object cannot be printed readably.

Also, Common Lisp has to serialize values into FASL files when compiling them, but it can do it only for its own types. You can use LOAD-TIME-VALUE to have a form evaluated at load time, and MAKE-LOAD-FORM is a generic function that you can specialize to print a form which, when read, allocates and initializes objects at load-time. For your own classes, it is sufficient to use the helper function MAKE-LOAD-FORM-SAVING-SLOTS.

All that gives you a lot of control over what, how and when forms are evaluated and stored. The good news is that you have libraries available to do that very easily: http://www.cliki.net/serialization (see for example http://www.cliki.net/cl-marshal).

See http://clhs.lisp.se/

And Lisp even offers good ways for most structure (even circular structures!) to read data in without enabling generic code execution.