A question to those of you who already looked at VS2010. How big are the changes that add-in developers will have to make in order to get their add-ins working under VS2010?
We've already migrated a development version of our Visual Lint product to VS2010, and for the most part the migration was straightforward - or would have been if there weren't so many bugs in the Visual Studio 2010 Beta 1 automation model. The experience has been akin to the work we had to do to support VS2005 (by contrast VS2008 was a breeze), so it's obvious that VS2010 represents a major change in the evolution of Visual Studio.
As we're using the same binary for all versions of Visual Studio we support (which means the code is contstained to be native C++ throughout), breaking changes in the interfaces tend to be quite visible to us. This time, the areas which have caused us issues are:
I suspect that our experience will be pretty representative for most add-ins - it is only if you are using the areas affected directly by major changes in Visual Studio itself (e.g. editor or intellisense integration) that the effects are likely to be particularly severe.
Finally, we're not planning to migrate the build itself to VS2010; it is currently built in VS2008, and we quite simply can't see any reason to migrate to an IDE which is showing every sign of still being a "work in progress" even when it RTMs later this year (that's just my personal opinion though - YMMV).