There is no more Business Intelligence Development Studio (BIDS) in SQL Server 2012, instead it has been replaced with the SQL Server Data Tools that uses the core of Visual Studio 2010, with the Report Builder and Report Designer built in to the new Visual Studio.
The UI has changed colors, and looks a bit sharper, but overall you have similar functionality as before with a few new features. Anyone who is used the the 2008 or 2008R2 report builder will have no problem here. For those moving to this from 2005 or earlier it might be a bit of a surprise.
This is also a good time to mention… Please take a look at the Database Health Reports project.