This is a really minor version just to cover some minor differences in the trx generated with VS2012.
The first thing to mention is that VS2012 does not generate trx from the IDE, so if you still want to have those files you need to run your tests from the command line using MSTest.exe or vstest.console.exe, one point to note here is that if you run the same tests, the trx will have some minor differences, like the abscence of "NotRunned Tests" when using the new tooll (I will cover those differences another day).
When VS2012 was in beta I asked to the product group if they plan to make changes to the trx schema, and they said that the schema will be the same, however they changes some values in attributes, so instead of naming a class with the full name, they removed the assembly information, and this is why the tool generated and exception.
I have fixed that bug but I did not run the regression tests, so use it at your own risk !!