Its fun but the problem is there are alot of rules and if you make one of the many mods mad you are banned. o btw, it costs $10 to be a member and if you get banned you have to pay again...
DP is focused on webmasters, I think it's the biggest and best forum. Others like Sitepoint may have more active users, but the focus is different.
Quality counts... Groups are huge too... But it's all SPAMS. You hardly get any useful information from it.