Update, 30.09.2017: After trying it again today, I found none of the problems listed below anymore. It's fast and painless. So that's good!
It was bad before, but after the upgrade to Ubuntu 16.04 – which may or may not be related, it probably is – it went from bad to downright painful. Connecting device and PC works fine. What does not is …
- It is slow. Opening the SD card directory with my music takes several seconds.
- After deleting files the amount of available space is not updated. I free space for new files but get a warning telling me there isn't enough free space. At least I have the option to try and copy the files anyway, ignoring the warning.
- The new problem: After just one transfer, I cannot access the device per MTP anymore. No content is listed for the music directory anymore. Seemingly trying to load the contents it ultimately fails to do so. Unplugging does not help. Restarting the PC does not help. Restarting the device does not help. Using a different PC with macOS does not help. What helps is … using the Android file manager and deleting a file. Something is seriously broken here.
In early Android versions the device was mounted as USB mass storage. Those were the good, old days. At least they had understandable reasons for replacing it.
An alternative to using MTP is FTP. I used the app FTPServer to start an FTP server on my device while connected to my home WiFi. In the FTPServer settings I chose
wlan0 as standard interface and pointed the server root to the directory
/mnt/extSdCard. Now I can use FileZilla or Nautilus (see image above) to connect to the server from my PC. The transfer speed is of course a little limited, but the file transfer itself? – works just fine.
While I'm happy to have found a good alternative to the nightmare that is MTP, I find this whole situation quite ridiculous. At some point I'd like to upgrade from my Galaxy S3. While I'm not considering iOS or Windows Phone, I'm also disappointed of Android. Hopefully the Ubuntu phones take of.