JetBrains have made a 4.5.1 maintenance release of ReSharper available for download. It is a free upgrade from any 4.x version, and the Release Notes indicate that a large number of bugs have been addressed. Despite some issues I had with the Beta version I happily found the 4.5 release to be stable. I have been regularly testing the nightly builds and think that 4.5.1 will be a stable and reliable release.
A couple of highlights for me are that the default Naming Style rules have certainly been improved, with more options available for both private and non-private accessible members. Also, method names with an underscore are no longer considered erroneous, which was a problem for auto-generated event handlers in Visual Studio. It was also a problem if your unit test naming convention involves the use of underscores as a separator, like this one recommended by Roy Osherove.