Hi All,
Just a quick synopsis of my experience with the 4.0 framework.
I am coming from having a fair amount of code invested in the 3.1 version and so went to do a conversion.
This was, I'm afraid, abandoned.
XNA 4.0 seems to take out far too many helper functions and workflows and gives, well, nothing to the PC programmer. Formats/enums removed, breaking changes to vertex handling, the list is endless...
If there were a list, I suppose that'd be something. A mob of Shawn's posts in relation to this laid out hap-hazardly does not do much good when trying to approach an upgrade.
I also use 3rd party libraries - most notably XNAnimation for skinned mesh animations. The breaking changes ensure that these no longer work either.
I have to admit, I am not an XNA guru - never got too much into the content pipeline processes and importers, which was ok in the previous XNA versions. It seems that 4.0 has raised the bar as far as knowlege requirements in the underlying technology.
What has been your experiences with the new XNA?
Do us Casual programmers just have to harden up?
It seems counter-intuitive that the breaking changes come from feature removal, not extension.
For me at least, I think 3.1 is where I'll be until the libraries catch up.
Steele.

I'm currently attempting to write a game for the 360 in 4.0 with VS 2010, however I'd like to remove some of the code/objects into a library for future games(First person camera, a debugging text display, etc...). VS 2010 throws an error regarding the library that requires a .config file to be added to the game application to tell it to use the library.

I think PC developers are just expected to abandon XNA 4.0 and stick to 3.1 or go over to SlimDX.

Microsoft has taken the stance from 4.0 onward to remove almost all the PC-only features from the framework to keep the API more cross compatible between environments, despite the fact that they have several things that only work on WP7 and the 360. I kind of feel like the we're basically the odd man out.

I do quite like the changes where something hasn't been removed.

Machaira, I am somewhat surprised at your comments. You say that nothin has changed really for windows apps, yet I have experienced so many incompatibilities with my 3.1 code base that the effort to convert amounts to significant redesign and rework. I am not alone in this either, just check the creator club forums for a taste.
I work in web application in my day job, and one of the things we can never do, is remove functionality from the user - even if it is technically difficult when moving to new platforms. It is very poor business. But given the nature of change in programming, you can expect such things from time to time, but on this occasion, with the lack of cohesive documentation on the upgrade process, I find the upgrade a barrier, not an advancement.
Don't get me wrong, the tuts on the new stuff are great. The new bits are nice.
It's the workflow from existing to new which is poor. Where my project was at the stage of dealing in high level objects, now has to have it's basic objects and structures redefined.