[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] MJPollard:
So far, I've personally noticed the following recurring problems with CM 11 (and, by extension, Quantum). I'm not sure which, if any, can be addressed by PwnCakes; they're very likely going to need to be handled by the CM team.

1. Docks and audio are flaky. When I plug my phone into an iBolt car dock, audio through the phone's speaker is automatically cut off. If Bluetooth is on, any audio from the phone (such as Google Navigation) comes through my car's speakers when I'm talking to someone, even though the Bluetooth entry for my car specifically has audio disabled, and the global option to route audio through the dock is also disabled. This has actually been a problem for quite a while, going back to CM 10.2. (I don't know if the same issue affects desktop docks, but I'd wager that it does.)

2. Car dock mode doesn't always work. Plugging my phone into the iBolt is supposed to bring up Car Home Ultra. Sometimes it does, sometimes it doesn't, forcing me to "kick it in the pants" by pressing the home button. The problem is more pronounced in the latest CM 11 releases: car dock mode doesn't work at all, not even when pressing the home button. (The last Quantum release where car dock mode worked [mostly] was Quantum 3.36.)

3. The in-call screen is acting very flaky. When making a call, the contact photo sometimes doesn't show up, with the default "smiling guy" graphic displayed instead, and other times it'll flash back and forth between the contact photo and "smiling guy" when first making a call. Also, when making a call, it'll often show the recipient on the top half and "smiling guy" with "on hold" on the bottom half (as if in conference call mode, but I'm not making a conference call). Finally, sometimes the phone just refuses to disconnect when the hangup button is pressed, usually when I've initiated a call; I have to toggle airplane mode in order to force it to disconnect.

4. The "split" in-call screen (contact photo and hangup button on the left, control buttons on the right) when the phone is in landscape mode while plugged into a car dock is gone. CM 10.2 had it, CM 11 does not. To be honest, though, I don't know if this was a deliberate design decision or a simple oversight on the part of the CM team, thus I'm merely making note of it and not considering it an actual problem. (I'd give anything to know how to code for Android because I'm itching to rewrite that part of the code to give us a snazzier in-call screen!)

Issues #1 and #2 are annoying, but I've learned to tolerate them while also hoping they'll be fixed soon (#2 is why I've gone back to Quantum 3.36: I need car dock mode to work, and it's not working at all on Quantum 3.5). IMHO, though, #3 is more serious, and needs to be addressed ASAP by the CM team.

Note that I am in no way blaming PwnCakes for any of this; he's been fantastic with all of his hard work on Quantum and its kernel. No, the blame for these problems (and others, like the ongoing LTE nonsense) I lay solely at the feet of the CM team, who are continuing their long history of putting out a new major release that completely screws up what was working in the previous major release. The transition from CM 10 to 11 has been no exception, and it becomes more and more aggravating as time goes on. :(