I only just discovered that you can try out Gimp 2.7.4, the latest 
version of Gimp and a step closer to the fabled Gimp 2.8 I've been 
waiting for. I was off to a bit of a rough start, but ended up over at 
Partha's Place (http://www.partha.com/) where he has provided binaries, 
many thanks!
After an hour or so playing around like a 
child with the new toy he's been waiting on since the last Christmas 
I've got mixed feelings. I really like some of the changes and new 
features yet at the same time the whole thing feels much more clumsy and
 harder to use.
Take the "Paint Dynamics" for example: 
to change the curve of the pressure-dependent size dynamic you must 
locate the Tool Options window, click on the Dynamics icon which will 
then bring up a quick menu containing the Dynamics presets, click on 
another
 Dynamics icon, this time small and right down the bottom, then the 
"Paint Dynamics" window will appear, you can then either double click on
 an entry to edit it (keeping in mind it will edit that entry for 
all
 brushes which use it) or click on the "Create new dynamics" button 
which will bring up the old "Brush Dynamics" menu that used to rest in 
the Tool Options window, you must then click on Size-Pressure to enable 
pressure dependent size and then near the top you must click on the drop
 down menu with "Mapping matrix" written on it and select size. Sorry 
that sentence was getting far too long, ran out of breath. Next you must
 manipulate the curve to produce the results you want, also keeping in 
mind that it doesn't tell you anything, which axis is pressure and which
 is size? Up, down, left, right? Sorry, that's as confusing and time 
consuming as the process I just described, a picture might convey things
 better:
That's
 simple enough, right? But what are we comparing it to? What I just 
described is basically the same thing as the "Power" slider in Gimp 
Painter - oops, I just gave away the end of this story didn't I.
Let's take a look at that same process in Gimp Painter:
I
 don't want to end on that note of course, I'm very grateful to everyone
 who contributes to Gimp, I love the program, but the new interface 
needs a lot of streamlining.