The service pack includes many bug fixes and new features. Important highlights include:
• V-Ray RT GPU: added a CUDA engine, in addition to OpenCL (requires a Fermi or Kepler card and the newest nVidia drivers);
• V-Ray RT and V-Ray RT GPU: support for motion blur (transformation and deformation);
• Added a set for renderable curves (like the object properties, displacement, etc.);
• VRayDistanceTex for Maya and Standalone.
See the full list of features and optimizations in V-Ray 2.4 for Maya.