What do you think of PHPBB as a forum CMS?

Hello,
I know it is a little off subject, but it is still in the website field. I am wondering what everyone thinks of PHPBB as a forum software? It is easy to use, is there good support, is it easy to customize and theme?
Do you recommend something other than PHPBB? And well, Vbulletin, because my budget is nothing.

Thanks.