I can chime in here, properly for this thread too. Seriously lets not turn this into "well only you have problems" because IT IS NOT TRUE by any means. If that's what you want to post, please just keep it to yourself.
Indeed, "many" people don't have problems. However those same "many" people are simply not using the features as advertised, or they "accept" things because of the rest of the WoW factors involved in with their new ride. Friends mom has a Mazda 3 with the same Infotainment setup, she doesn't notice any of these little things because the radio plays when she turns on the car and she's all smiles in her new car. Never notices anything else. I came from a perfectly fine 2010 (expect it being smashed by another car) so I expect top quality in the new features in my 2014. They have been very lacking, making me upset that I had to buy the new model year before the kinks were fixed. I bought a BETA product and I know it. I live my life as a daily BETA tester, and I too have had the system lock up/reset on me going down the road in the past. So absolutely embarrassing for Mr. PCGUY to have to pull over to "reboot" his car.
My background - I'm a senior computer analyst. I setup and configure complex shit all of the time for sensitive lab equipment, whiny PhD's, etc. My job is to find those weird details that other people don't see. Solve the complex issues that others can't grasp. It's so hard for me to accept watching the screen and seeing these silly problems since that's the type of thing I ensure our users at work DON'T have. There are indeed issues with the system, no doubt about it. Some people simply see more of the issues than others for many many factors.
I'm on v31, have had several software updates. I also have new TAU software and a newer/different hardware build than many people I've seen here.
MY PERSISTING ISSUES with v31 (I could write a massive list but I'll focus on what still happens that I've seen since my last update).
-USB playback of MP3's can be unpredictable. This has been ongoing since v2x for me. With previous versions, I've had an issue where when many songs change (on it's own, not by command) it plays about ~1 second of another song before playing the proper song. The screen does not signify this at all, you only hear it. If it's on RANDOM then what you hear is ~1 second of between songs is some totally random other song. If it's NOT ON RANDOM, you hear ~1 second of the next song, then it starts again and replays the ~1 second when the actual song info pops up.
I have a theory as to why this (and perhaps other USB issues) may happen. I believe the Mazda software puts far too much weigh into how long the ID3 tag says the song should be. I know some of my songs have tags that are slightly off, because I've found them. Hell, most people have have some songs like this especially if they've been collecting MP3's for years. It's most prevalent when an ID3 database lists the song length with it's ~second of silence at the start and end, then the copy of the song you have doesn't have the silence. To ANY OTHER MP3 player this doesn't matter, but the Mazda chokes on it.
-USB playback seems to have become worse with v31. Now along with the above problem, all songs kind of skip/jump about 5 seconds into the song for a moment or 2. It has already loaded the album artwork when this happens as well. This has never happened before until v31. It's embarrassing for me when passengers even notice this, since of course I'm bumping the BOSE as it's meant to be and there are obvious stumbles.
-USB playback, if a file has multiple pieces of album art attached (some simply come that way), the system literally freaks out. I have 3 Static X songs that are like this, and I know anytime they come up because the system freezes for about ~25 seconds of silence when it comes on. Once it starts to play, the info on the screen is all over the place. I've literally watched the seek bar (where it tells you how far into the song you are) go negative on these songs. It never really corrects it's self until you get to a new song, which also takes several moments to do since the system keeps freaking out the whole time it plays these.
-Audio commands. When I first got v31 installed I played with this, and it surprised me how well it worked for some things. At first that is, then it seemed to become more "dumb" (as other threads have noted it suddenly acts as if you are talking another language and can't understand anything properly). I didn't use it much prior to v31. I tried to call Mom the other day, pressed the button, entire Infotainment quit without any "please say a command" prompt. Hard lock, no buttons did anything. Screen still on. Audio went silent. Had to reboot the car. Tried it again, and it happened again. I've been able to reproduce this several times, no idea why suddenly now. Tried it out yesterday, it prompted me for a command, then what I said got completely translated into things that are no where even similar to what I was saying. Telling it to go "back" resulted it in it playing some wild song that sounds nothing like what I said to do.
-Bluetooth. It seemed to get better with my new TAU, however I still have the dreaded "unable to retrieve messages" or whatever error for texts. Literally, I can get a text, it reads it just fine. 5 mins later, get another text and it's unable to get anything else from there. Once it's unable to retrieve, it can never retrieve until a car reboot.
-Bluetooth, I have email notifications enabled. I've never seen it work once. Ever. Granted I don't mind, but I do have it enabled and regardless of it's an IMAP email, Gmail email, etc it never lets me know as it says it should.
I'm running Android 4.4.4 on an LG G2 (Verizon). I'm using AOSP (Android open source project) so I'm literally running the most vanilla Android you can get, no extra junk from LG, no thrills from Verizon, no custom GUI, no crazy extra phone addons, vanilla Android. It's super sleek and fast, and basic just the way I like it. The fact that it can work perfectly fine one moment, then quit another really shows that there is an issue here. These issues have persisted since Android 4.2 for me, across various builds of AOSP from different developers.