I've been using 8.2(1) for my ASA 5505 for almost 3 weeks now and I don't encounter any issues. Also it fixed my problem with phone proxy relating to the one-way audio since it got new features of getting the MTA on the interface (in/out). I also have site-site vpn runnning along with the phone proxy with no problem at all.
the only issue I have with phone proxy is not getting the extension mobility to work though it displays but that's not an issue with the firmware itself.
hope that helps.