Update: after removing all community mods I had added to my CookedPC folder (including Troll Trouble), the version check passed and the installation was successful.

*sigh* Downloaded, unzipped, executed...

Critical Error
Failed applying patch change to 'X:\The Witcher 2 Assassins of Kings\Launcher.exe

And now the launcher itself refuses to run...

I do have some mods im using the widescreen fix, geralts white hair, mostly cosmetic mods, so im reinstalling now and will use the patch officially on GoG site. I am installing it to my E drive but the path is still standard, once its installed ill post here before i install any mods or change any setting if the patch was successful.

Yeah, I'm waitin' on the patch notes.

The .dzips, (merchant, troll, ...) not the mods cause the invalid version problem.
Removing them made the patch proceed. Better use the .dlcs anyway.

I had the same error because the launcher was active. After closing it the patch installed successfully. Yay! :) Close launcher before installing patch.
Got it! Installed it! Thanks Coala! :)

Well done GOG!

I found something like this:
http://mygaming.co.za/news/pc/11957-Witcher-version-incoming-patch-notes.html

found this in my readme GOG edition

2) Patch 1.1 Corrections

1. The process of installing and activating the game is now easier and more stable. SECUROM copy protection has been removed entirely, making the game DRM free!
2. The ôTroll Troubleö DLC package is included in the patch, bringing to an end any and all problems related to downloading this content.
3. Problems related to downloading other free DLC have also been resolved. The game launcher now correctly detects and updates specific modules.
4. Game efficiency has been improved. Game now runs 5-30% more efficiently and game loading has been accelerated. Efficiency increases will vary depending on system configuration and game version. Owners of boxed versions of The Witcher 2 are likely to notice the greatest improvements.
5. Bugs causing the game to crash, especially while saving game progress or loading saved games, have been corrected.
6. Movement key mapping has been expanded to include cursor (arrow) and number pad keys.
7. Options have been added for inverting the X and Y axes of the mouse.
8. NVidia 3D Vision Surround now works correctly with the game.
9. The hardware configuration auto-detect function has been corrected, resulting in improved game efficiency.
10. A bug preventing the completion of the ôBlood Curseö quest has been corrected.
11. After beating the GOG.com penitent monk in the mini-game, the relevant link now displays correctly.
12. GOG.com credits have been corrected.

If you have encountered problems not covered by any of the fixes listed above, please bear with us. We are working a second patch, designed to correct another set of problems and bugs, including those related to specific hardware, e.g. Logitech G35 headsets. Look for the next patch towards the end of May.

Yes, that's the incomplete list that they promised to expand once the patch goes public.

Thanks for that.

Patched without any issues.

Slight increase in performance for me, but then it was already running pretty smoothly.

those really arent a lot of changes

It was out in only one week..... They also have confirmed a second patch is coming. Wow. The impatience around here.

Does not list all of them. Atleast I can now launch the game on my native res without dropping desktop resolution down to 1920.

now if we could resolve the lightning issues we people with crossfires/slis have would be aweeesome :-)

something i've seen is that sometimes fps go down without any real reason, alt tabbing makes the fps go perfect again... strange behaviour but not so problematic. One of the places it happens for me is getting out of the tent in the prologue. It's usually 60s there but sometimes when loading the save it's on 30s until i reload my save or alt tab and reenter. Don't if it's something to do with the ati hotfix that should be improved with the CAPs that's expected to be released tomorrow of it's more like the engine fault

using CF 5850 the game runs between 50-60s nearly all the time except some places with lots of people like floatsam plaza where the fps go between 40-50s. Ubersampling and motion blur disabled

Removing suckarom is a lot IMO. :)
Fret not! There will be patch 1.2 :)