I have been using CTP5 of VSTS4DBP for a few weeks now and have come across alot of problems with it. They are:
1) Schema import and schema compare require pretty strict permissions in order to run. If those permissions are not in place you don't get a nice error message, you get a Visual Studio crash. (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=686554&SiteID=1)
2) SQLBuild and SQLDeploy tasks from MSBuild.exe don't work properly (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=753841&SiteID=1)
3) If VS crashes (for whatever reason) then you run the risk of entering an unrecoverable state (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=785288&SiteID=1)
4) Not possible to remove objects from schema view (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=776174&SiteID=1)
5) Doesn't understand CTE syntax (can't find the thread but its there somewhere)
6) Doesn't create CREATE USER scripts correctly (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=776385&SiteID=1)
All of these problems have been fixed in CTP6 which is due in the next two weeks (apparently). So my recommendation is to hang off from using the product until then.
-Jamie
UPDATE: Also bear in mind that any projects created in CTP5 cannot be opened in CTP6 (https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=785963&SiteID=1).
-Jamie