No ugly popups.
The directive does not allow non essential cookies and tracking cookies, but if cookies are used for a service requested by the user (ie. being a member of the forum), then cookies are fine.
In Web Wiz Forums case it means that cookies are only set for logged in members, non members would not have cookies set on their browser.
The biggest impact is for non members the last visit date is not stored in a cookie and so the forum can not show non members the posts since their last visit.
It's been tested on here and other forums for months and no one has noticed any difference, if they have no one has said.