Gimp 2.10.0 RC 1 is out!
Announcement → gimp.org/news/2018/03/26/gimp-2-10-0-rc1-released/
The amount of fixes and new features is great, but this post isn't about that... =)
If you happen to start this new Gimp and are, like I was, horrified by the look, know that in the preferences you can still choose the "System" theme which will probably make it look like you had it before. It certainly did for me, using my Oxygen widget theme and my own (dark) custom colors.
Same thing with the icons, which now seem to default to a monochrome/symbolic set (because that's the current supercool fad, right?), but you can still select the classic theme, plus now you can set their size!
EDIT: 2.10 final is out! These tips are probably still relevant xD