VS 2008 - It does increase productivity...
It has been two weeks or so, with using VS 2008 (Beta) exclusively and to date have not used the VS 2005 to do any coding.
While I really see no use for LINQ and some of the other newer technologies (mainly because I code for performance and not ease of coding such as using master pages etc - instead I would rather craft the code to do what it needs to do with the least amount of perf hit as possible).. there are some really cool productivity enhancements with VS 2008.
The first: The split view of code and design when working with .aspx and ascx files. It was always a issue with earlier versions that one couldn't switch to design view because of some code behind or missing control. Now with VS 2008 you can display both and find and correct issues without worrying about the 30 second pause and message dialogs... The designer even includes a intelligent 'refresh' button for the designer so you can verify in real-time that designer and the code are in sync.
Secondly: The ability now to not have declare private variables for public variables. The old: private int _myTest; public int MyTest { get _myTest, set _myTest = value} is now simply public MyTest{get;set}.
What a savings on coding... see Scott Gu's blog for details..
Third.. Compiling huge projects is incredibly faster. One solution I have under VS 2005 would take 5 minutes to compile, with VS 2008 - less than 30 seconds... no more having to brew a cup of coffee to await the results...
Find and Replace however still suffers the same issues as previous versions. When you click on Quick Replace, and then Replace in Files - it will change the selection for whether it should target solution, project, selection, etc.. and in some cases replace what is supposed to be replaced (in the dialog) with the previous replace text... A somewhat major annoyance at times but the undo does actually work more efficiently than previous versions...
The one thing I wished was there would be some kind of breaking changes document describing what is different with 3.0 / 3.5 and the changes to the core 2.0 (as it applies the service pack)...One of the decent things at least the whole Ajax implementation did between versions - was outline breaking changes, and new features.. The Visual Studio section on Microsoft's site really doesn't provide such info in a simple document...
Overall though, fairly pleased with VS 2008...