I have various 64bit and 32bit machines all running LMDE (UP3). Stability and reliability is key, so I have them all locked to gnome2-frozen while I test UP4 on a spare test machine. I did a UP3->UP4 upgrade on that test machine a few months back. I do like UP4 w/ Cinnamon, but I had dislikes with Cinnamon and was hoping to let it matures a bit more. Some of my concerns was that I lost all my Compiz compatibility (I have a lot of optimizations in Compiz that improve my productivity), the task bar doesn't adjust, so when it becomes full, it pushes the quick launch icons and menu bar off the screen, and sometimes when dialogues or windows load, they leave gray-artifacts behind on the screen that obstruct all other windows until I close the offending application (which can be a serious productivity killer when I have to close applications twice a day). So, I wasn't ready to upgrade.
Gnome 3 wasn't really an option as I tried it last year via Mint 12 and had serious stability issues that were documented by me and countless others, about gnome-shell freezing or resetting on itself (and losing all application work currently open). So I wasn't going to even give Gnome 3 a try in LMDE UP4.
Now that gnome2-frozen is dead, I have no choice but to upgrade. I don't know how I missed MATE in UP4 (I did try gnome-classic). MATE is exactly what I'm looking for -- it's fast, provides all the look and feel I've become accustomed to in UP3, and it works with Compiz, so I don't lose my productivity optimizations.
So I started upgrading my systems to UP4 today, thinking it should go smooth.
I wanted to try the upgrade via aptitude because one of my 32bit machines is purely a command prompt machine, so I wouldn't be able to update it using the mint update manager (at least not easily). So I wanted to verify the upgrade path would work through aptitude. I did an apt-get upgrade & apt-get dist-upgrade. But it proved to be very problematic (in the end at least).
Issue #1: I'll just skip over this one quickly since it was really a side-effect of a kernel upgrade as part of the upgrade (and nothing to do with mint), but I had issues with the new kernel that was installed. The system would hang at black screen when loading gdm3. I could get to command prompt if I avoided the system from loading gdm3, and I could startx to get into a session, but gdm3 either on startup or from command line resulted in the system freezing at a black screen. I was keen enough to suspect a i915 kernel module issue, and doing a comparison of the loaded parameters between the old kernel and new kernel for i915 indicated a new ppgtt parameter that was loading a default=true. So once I overriden this to false, my issue was resolved.
Issue #2: MATE or cinnamon didn't install, only gnome3 and gnome-classic had installed. I needed to go through the forums and track down all the packages associated with MATE and cinnamon to manually install them. The test system didn't have the issue, so I'm thinking this might be a side-effect from using aptitude then the gui update manager? I want to do the upgrade consistent across all my systems, and since one of them I only connect to it through SSH (gui disabled at startup), I wanted to use the command line aptitude upgrade path (which I researched what I needed to do and did not see any catch-22s with using it). If it is deemed that this should be avoided, then what other options do I have? I figure aptitude is safer than trying to forward X windows over SSH.
Issue #3: I lost my panel and all other customization via the upgrade. I had to rebuilt my panels etc in MATE. When I tested this on the other machine from going from UP3 gnome2 to UP4 with Cinnamon and MATE, my panels remained in tact other than the quick launch panel in MATE. I reconstructed my panels layout from memory, so this doesn't remain a sticking issue, other than the fact I'm going to have to spend an hour+ on each additional system I have to upgrade if this happens on them as well.
Issue #4: gdm3 is displaying the debian-twirl icon instead of the mint icon. A few other icons throughout the system are debian-defaults rather than the mint ones. I compared the greeting config file between this machine and the others and cannot locate why this is happening and how to get back all mint icons.