Hi Site,
You've obviously seen a phpBB3 site and know the cosmetic differences ?
Behind the scenes there has been a change in the code to make it more secure but as a user the other changes are too many to mention.
Some to note though are Mods accounts - They have their own control panel which you as admin can give whatever powers you see fit.
You also have the new Permissions which believe me take some working out !
Finally the whole of the admin panel is set out in tabs like IE7 or Firefox with the tabs at the top.
You need to have a look at a phpBB3 site behind the cover to make your own mind up.
There are various Portals available in Beta [Test] which appear to work.
One I have tried is
phpBB3 Portal
If you want to see this up and running PM me and I'll give you admin access, can't say fairer than that !
That's your lot,
Jon