I believe all ril-related SoDs are now fixed in my ril.
Haven't tested Call Waiting, but that may turn out to be a ril-related bug too. I can probably investigate it later.
Data Connection - should be 100% reliable now.
MMS - reception on CDMA has improved with the new ril in real CDMA mode. You get the message and a download link, but thus far no one has gotten the download link to work. Seems to be a framework/config issue; the ril-related pieces are all now in place. Probably needs a profile to be updated using ##3282# or similar.
GPS - the bug where it always starts with your position in the middle of the ocean has been fixed. Aside from that, it's still a slow startup.
http://forum.xda-developers.com/showthread.php?t=969761
Clock - if your network supports Network Informed Time Zone updates, you can get the clock set automatically whenever your phone registers to the network. So far it looks to me like GSM networks only send these updates once, at initial registration. However toggling Airplane Mode on and off causes another update. On CDMA networks you can get NITZ info much more frequently, but right now the RIL is only set up to process the update from the initial registration. I think parsing every single received NITZ on CDMA would be overkill. (It's sent with every tower status update message, along with the tower lat/long coordinates.)
Tethering over USB - I have a hacked adb binary that sets up a ppp session over an adb session. (The regular adb binary will set up a ppp session using a tty device on the phone, e.g. to talk to the phone's radio.) I use my hacked adb to tether between my phone and my laptop.
http://forum.xda-developers.com/showpost.php?p=4537323