Documentation is sparse, but the API mirrors the well-docmented Java original. However, my OS X build fails at the second hurdle with the message 'abort trap,' which is not documented anywhere I can see outside of the cpp source.
AFAIK, this module is deprecated in favour of Kino Search, which is not compatible with Lucene, but performs the same functions as well as any Perl module could - highly recommended.
Great module. The api is almost exactly the same as the java one.
I tested it in a persistent environment ( mod_perl ) without any major problems. I use it with a couple of Gigs index containing millions of documents and it delivers astonishing performance.