Quote:
There's a cage tool that distorts badly, some filters which are old third party filters included by default, a second rate bunch of brush presets that doesn't remotely compare to the quality presets in GPS and the new tool sliders are impossible to get hold of with a Wacom and impossible to adjust finely.
Hy mate i understand your frustration but i feel also directly criticized because the
" filters which are old third party filters included by default" exist only in the Partha portable version and in my "windows friendly "version (did i send you the link?)
and i contributed to both ( in particular to suggest what to include and test compatibility )
And of them only very few are "old", (if old maybe are included because still rocks

) most are recent and in the very last version, and in same cases was not a build of that very last version before
BUT the basic point on "filters which are old third party filters included by default" is that athey have nothing to do with gimp 2.8 as planned by the developer they are included by me and partha because a peculiar concept of packaging:
what should be in gimp but could not be in gimp for the developer need to maintain the code the most simple and compact.
And the idea is that at packaging time, respecting the developers need, what was excluded may be integrated at binary level without complicate the original source code.
I could avoid to reply to that point because i am one of the main responsible, but i know for you was a marginal point, maybe slipped in to give more emphasis (
and no..i don't feel offended 
...i just wanted clarify )
so now back to the real basic point of your message
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you are right on the fact that the most promising changes (16 bit support, adjustment layers ) are posponed to a uncertain future (gimp-3.0 or even gimp-3.2) and that is delusive
still there are a lot of changes to quote a few
option for single windows layout (you may not care much about, but was very requested )
new text tool (i don't use much so i can't say how much is better, but looks more powerful and flexible)
new brush engine (that doesn't modify only the brush tool but all tool using brush, from the eraser to dodge&burn )
Old and relevant bugs in the Layer modes ,for color & and overlay mode ,fixed (even if only in Gegl operations)
Layer group , for sure this is very relevant when working with many layers
About weirdness in the new cage tool...maybe the will to fix that could be one of the reason of delay of the 2.8 release
b
And about GPS it can't be used
fully on gimp 2.7-2.8 and Ramon is working to adapt to the new release
it was a dilay because a new bug in the new GTK that screwed up the support for graphic tablet, the bug now is not really fixed but is somehow minimized, so now could make again sense try to port gps to gimp-2.8