OK it's my post. I'll answer with MY point of view and personal advice 
This tool not only degrades pixels, but you do not have any true controls on it and the few videos speaking about it you saw on Youtube are made by people which have no idea what they are doing! And they show you only the "growing"...
First of all if you want to use it properly you do need to cut out the part you want to transform and put it on a new layer , because you will spend time cleaning edges and artifacts. (tip: do not forget to put that new "pasted" layer at image size before starting to select/put nodes)
If you don't cut out you will get this(below): Good luck to clean the mess...
Secondly, it degrades pixels badly and quickly... more than the other transform tools.
As an image is worth thousands words.
Selection is only straight lines...
Algorithm to transform is... WTF
below just inverting corners, top left -> bottom left, and vice versa, then top right to bottom right and vice versa...
What is that???? (OK it might be only me, as I have to use the Krita's mesh transform tool for extreme transform that GIMP can't do -> http://gimpchat.com/viewtopic.php?f=8&t=19437 )
Also why this tool left some part of the image below? with artifacts....
And so...
But... Today...
---------------
And because of you, I did tried it today for the screenshots...
Let's face it, it's better, faster and did not bug as it has to use (GIMP 2.10.30 PPA from Jim),
So I will look a bit more into it with this last iteration of GIMP and may be less criticizing it to some extend
Thanks @Redraw for forcing me to re-discover this tool.
This tool not only degrades pixels, but you do not have any true controls on it and the few videos speaking about it you saw on Youtube are made by people which have no idea what they are doing! And they show you only the "growing"...
First of all if you want to use it properly you do need to cut out the part you want to transform and put it on a new layer , because you will spend time cleaning edges and artifacts. (tip: do not forget to put that new "pasted" layer at image size before starting to select/put nodes)
If you don't cut out you will get this(below): Good luck to clean the mess...
Secondly, it degrades pixels badly and quickly... more than the other transform tools.
As an image is worth thousands words.
Selection is only straight lines...
Algorithm to transform is... WTF
below just inverting corners, top left -> bottom left, and vice versa, then top right to bottom right and vice versa... What is that???? (OK it might be only me, as I have to use the Krita's mesh transform tool for extreme transform that GIMP can't do -> http://gimpchat.com/viewtopic.php?f=8&t=19437 )
Also why this tool left some part of the image below? with artifacts....
And so...
But... Today...
---------------
And because of you, I did tried it today for the screenshots...
Let's face it, it's better, faster and did not bug as it has to use (GIMP 2.10.30 PPA from Jim),
So I will look a bit more into it with this last iteration of GIMP and may be less criticizing it to some extend
Thanks @Redraw for forcing me to re-discover this tool.