Everything works out of the box except the touchpad (i think people now begin to call it clickpad).
It is quite strange that the clickpad has no problem during live installation session.
Once I reboot, it stopped working. External mouse or touchscreen (with stylus) still worked fine.
After some googleing, I found the solution just 3 steps to blacklist i2c-hid module as described here:
It worked for me.
synclient -l | grep Offcriterion described at http://ubuntuforums.org/showthread.php?t=2245674 didn't work for me. For me, it is always
TouchpadOff = 2, regardless of whether the clickpad works.
I just feel puzzled why the clickpad worked fine during live installation session but not on the one booted from my hard drive.
A detailed look is at http://askubuntu.com/questions/527793/clickpad-not-working-on-dell-inspiron-13-7000-running-ubuntu-14-04
Another lesson I learned was that Ubuntu Mate 15.10 (daily build, fetched on 06-21-2015) installation program seemed to have problem on writing into EFI partition. So after installation, I had no option in UEFI to boot into it. I am not sure whether the problem is caused by Ubuntu 15.10 or the Mate fork. I tried Ubuntu Mate 15.10 is because I like the lightweight Mate environment than Unity.