I used to sue it, until I decided not to waste precious processor cycles on my windows friend. It is as decent of a AV as you can get, it uses the ClamAV engine, which has a much wider implementation than just ClamXav (I seem to remember even apple uses it in OS X server versions), making it quite trustworthy and sure to have the latest databases.
In conclusion, if you must use a AV in mac, I would go with ClamAV.