It allows Subversion to use any of the numerous authentication systems already integrated with Apache.
There is no need to create system accounts on the server.
Full Apache logging is available.
Network traffic can be encrypted via SSL.
HTTP(S) can usually go through corporate firewalls.
Built-in repository browsing is available via web browser.
The repository can be mounted as a network drive for transparent version control (see Autoversioning).
Noticeably slower than svnserve, because HTTP is a stateless protocol and requires more network turnarounds.
Initial setup can be complex.