An artist in Deviantart with profile name 'doctormo' published an awesome tweak which let's you to change the user-interface of the GIMP something similar to world popular image editing software Photoshop. This tweak currently works on GIMP 2.8 .It does works for GIMP 2.9 but some features might be missing
Steps To Installation :
1) Download Tweaks.zip from Official Page.
2) Make backup of your current GIMP configuration (Just incase if anything goes wrong, you can back it up). To do so, go to /home and press 'Ctrl+h' it will show hidden files. Now copy entire folder named '.gimp-2.8' to anywhere but /home
3) Extracted the downloaded .zip file
4) It will contain file named .gimp-2.8
5) Simply copy that file & paste it in /Home & overwrite it on current .gimp-2.8
And you're done!
NOTE : You can perform this tweak in Windows & OS X operating systems too. I don't use Windows nor OS X so I don't know how to do it. But I guess from these steps you can figure it out on your own.