I recently wrote an article on SQL Server Data Tools for SQL Server Magazine and it has now been published online at Get to Know SQL Server 2012's SQL Server Data Tools. In the article I offer my thoughts and opinions on SQL Server Data Tools as it exists in SQL Server 2012.
Note that the article refers to SSDT database projects only, there is nothing in there pertaining to SSIS, SSAS or SSRS. If you find that confusing then you should probably go and at least read the first few paragraphs of the article where I try to alleviate some of that confusion.
Constructive feedback is, as always, very welcome.