When I select next or back, the volume is reduced so low I can barely hear it on my system. However, if I let rhythmbox play continuously, the volume remains the same. This doesn't happen with rhythmbox-0.12.1.
Workaround seems to be enabling cross-fading between tracks. Usable for me once I do that. Not sure if this is still a bug. I've never needed cross fading enabled between tracks in the past.
*** This bug has been marked as a duplicate of bug 510499 ***