I have been moderately content
 with Ubuntu 14.04 on the Acer Aspire E15 for about a year. Ubuntu 16.04 LTS, another long term support release, has recently been published and of course I had to try it out!
Installing the live image on a USB stick: bring some patience
The first obstacle is that there is no obvious upgrade path
; USB boot media created with the “startup disk creator” fail to boot with the message “not a com32R image”. In short, the USB stick creator can’t reliably create bootable USB sticks for other OS versions that it’s running on. The solution
 is to still boot from the broken USB and type “live” at the prompt which runs the live image; that’s enough to try the new Ubuntu out.
Installing to an USB stick and booting from it is horribly slow; while the USB stick I used allowed consistent sequential write speeds of 10 mb/s, installation staid most of the time at 3 mb/s. When the live image boots it is still bogged down by the slow write speed to the USB stick which makes even web surfing slow. However the system runs stable which is enough to roughly test the system.
I was able to repartition the harddisk without losing data and install Ubuntu 16.04. Unfortunately upgrading wasn’t possible, so I backed up any data and imported it once 16.04 was running.
The good news: the system runs quite stable and feels faster than the old 14.04. Power consumption is at 12,6 Watts when booked into a WLAN, with maximum screen brightness and all Powertop settings enabled.
Some obstacles to work around
Initially empty software store
The software store is empty before adding more repositories in the software updater, updating and rebooting.
Firewall GUI not starting
The firewall GUI fails with this error:
File “/usr/share/gufw/gufw/view/gufw.py”, line 19, in
ImportError: No module named gi
An “sudo apt install apt-get python-gobject” solves the problem.
No Nvidia graphics
Greatly frustrating: only the Intel graphics run; any attempts to enable the Nvidia drivers or even install Bumblebee to make use of the second graphics card prohibits the system from booting. The situation is slightly worse than with 14.04 where it was possible to install Nvidia drivers, they were just unstable.
update 2016.10.17: Some Nvidia graphics
Step 1: You’ll need bumblebee , which enables on-demand switching between the primary Intel graphics and the secondary Nvidia graphics chip.
apt install bumblebee
Step 2: blacklist the nvidia-358 module; to do that, edit /etc/modprobe/bumblebee.conf and add a section similarly to the other ones that are already in the file. If you don’t do that, the Aspire E15 won’t boot into graphics mode any more.
Step 3: edit /etc/bumblebee/bumblebee.conf and set “Driver=nvidia” and replace the nvidia-current with nvidia-358
Step 4: edit /etc/bumblebee/xorg.conf.nvidia and uncomment/edit the BusID to match yours. You find that one with
lspci | grep 3D
Step 4: Install the nvidia-358 package and only that; I couldn’t get it working with any other version.
apt install nvidia-358
Step 5: delete /etc/X11/xorg.conf
Step 6: reboot
A good troubleshooting guide is here: https://wiki.archlinux.org/index.php/bumblebee 
Intel graphics better than in 14.04
To make up for the missing Nvidia support, Intel graphics is faster now than with 14.04 where I still had to enable a Grub workaround to get it running reliably. Also Flash videos run delightfully smooth both in a browser window and in full screen.
Scanning devices works semi-reliably (sometimes they don’t show up), paired devices don’t show all capabilities they had in 14.04; e.g. I can only send files to my phone but not use it as an audio endpoint or modem.
Network manager doesn’t see WLANs after waking up from suspension
More of a nuisance than a problem, sometimes when the laptop wakes up from standby it won’t reconnect to the WLAN and the WLAN list will stay empty. A “sudo service network-manager restart” fixes this.
Hardware function check list
[X] Line in
[X] Line out
[X] CD ROM
[X] Bluetooth (partially)
[X] Graphics (partially)
[X] Wlan (partially)
[X] Hotkeys brightness
[X] Hotkeys volume
 Ubuntu 14.04 on the Acer Aspire E15
 How To Upgrade to Ubuntu 16.04 LTS
 Ubuntu 14.04 LTS live USB boot error (gfxboot.c32:not a valid COM32R image)