I ended up purchasing Pro a couple of weeks ago. I've spent maybe 20 hours in it so far. I don't see any negatives yet. The new UI style is quite a step up. The only new feature that I notice and appreciate is when you single click on a file in the solution explorer it will open it and place a temporary tab on the right side of the center pane, instead of opening it in the "permanent" list with tab on left during double click. This makes it faster to quick reference code.
Overall I bought it for access to MFC and various .NET features, and my need for those just happened to line up with the new release.
I know that's not much to go on, but that's all I can offer so far :) I would always recommend anyone stick with Express unless they have a need to upgrade from there.
I'm considering buying it (even though it is pricey here in Poland - ~$750), but i might try the Express version first. Also i'm writing mostly C code that causes Intellisense to trip over. The debugger though is a big help and i'd like to have access to stuff like MFC and plugins.
I recently did the jump from visual 2008 + visual assit to visual 2012 and it is really worth it. The IDE is far more responsive than the previous version and imho, i love the new layout.
They also mostly stole the visual assist key feature, merging the looking for file and symbol feature into the new solution explorer. They extend the syntax colorization far by more than visual assist too. I love to be able to distinguish between local variables, method parameters and class member for example!
The background code compilation to perform syntax error detection while typing code is also a really nice feature working really well with an intellisense that i will describe best as under steroids :)
As a graphics programmer, i was concerned with the new integrated pix directly in visual. They took a good direction, but up to now, it miss a lot of crucial feature and is mostly useless for advanced usage up to now :(
The good news is that Microsoft decide to not rely anymore on a model where they shipped visual versions sparse by years without any intermediate updates. They promise that with visual 2012, they will release regular updates to bring more features into the tools. As an example, They already mention they will add new C++11 core language feature and improve the graphic diagnostics pix !
How big of a change is the file format for project and solution files when compared to MSDev 2010 or MSBuild? We generate a lot of project files and I am trying to measure how big of a pain it will be when time comes.