HI,
I seem to have a problem with the microphone on my Hammerhead since switching to the release candidate. It fails to function when I make a call. However, if I toggle loudspeaker mode, then it works fine. Separately, if I choose to use the sound recorder, that works fine, but I suspect that's akin to loudspeaker mode. Previously, everything was working here. It's possible I had this happen in stable on one occasion, but I'm not asserting a link. It was early days using the phone when that happened so... meh.
I can't test this as much as I'd prefer because I'm too nerdy to have organic friends aside my inner circle of plants. From what I've seen with logviewer, the logs seem innocuous, but I haven't unhooked the phone (my sole internet connection) to examine dmesg in finer detail.