If you work with WSDL to access the SOAP API, then you need to be aware of the fact that there is a serious problem involving the Winter 15 release. As of now, there are two issues that are causing problems.
The first issue has to do with consuming an enterprise or partner WSDL in .NET. If you generate your WSDL using the new Winter 15 (or version 32 of the API), you should get the following error when you try to instantiate the object:
There was an error in serializing one of the headers in message loginRequest: ‘Unable to generate a temporary class’. Cannot convert ListViewRecordColumn to ListViewRecordColumn
This issue has been reported by multiple people on the forums. You can workaround it by doing a simple find and replace in your solution. You will want to do a find for all occurrences of  and replace with . This should replace two occurrences in the Reference.cs class file. You can then recompile and your app should work.
The second problem has to do with consuming custom WSDL and this is a known issue that has been acknowledged. A permanent workaround may become available, but in the mean time, the fix involves doing another find and replace. You will need to replace all instances of ns1: and ns2: with tns:.
Hope this helps someone avoid all the hair pulling out that I went through recently.