I used to work with Indigo and it was pretty good, but once in a while it's important to upgrade to have some new features so I was forced to install Luna.
First huge problem
Try to move the editor tabs: everything disappear. The entire Window turn to gray (on Windows some experience it as black)
A lot of flickering everywhere, even on other windows not Eclipse related (e.g file manager, pluma, etc.).
Slow, slow slow. My i7 workstation can't scroll the editor properly. What do they expecty me to use? A Cray-X Mainframe? When I use the down arrow, it's so slow that the keys are queued and I can't figure out when depressing the key to stop where I want to.
Solution Make a bash script like this one:
#!/bin/bash export SWT_GTK3=0 export UBUNTU_MENUPROXY=0 cd /opt/eclipse ./eclipse -showlocation
edit the launch icon of Eclipse to use that script instead of eclipse directly. Try it. No more flickering and good speed is back!
FIX the theme
With the above modifications the gtk menu will look a bit messy. To fix it, go in window→preferenced→general→appearance and set classic theme and that's it!