I have not picked this up yet because the first 2 is still in my backlog. I got about halfway into the first one before I lost my saves to a freak formatting accident. Should i finish 1 or just skip to 2?
I'd say that reading the books is actually more important then playing the games. Neither of the games explains the lore and Geralt's relationships as much as the first two short story collections, The Last Wish and The Sword of Destiny.
If you aren't feeling Witcher 1, then skip it. Look on the nexus mod site and download a completed Witcher 1 save so you can import it into Witcher 2, or I can give you mine if you like.

Read up on what decisions import and go from there. The items you get aren't that helpful, they become obselete with a few hours of play anyway. Of course you won't get all the references from the first game if you skip it, but thats up to you.
Remember, you're playing to enjoy yourself. When it becomes like a job, then you know something is wrong.
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If anyone gets that 'no disk space' error in GOG Galaxy after installing the retail version of TW3, here's how I fixed it:
1. Uninstall Galaxy
2. Backup TW3 files to an external or another HDD
3. Uninstall TW3
4. Do a search and make sure everything related to GOG is gone
5. Reboot and reinstall Galaxy
6. Copy your W3 files and import them via Galaxy
The updates and DLC should download then. That's the stragest bug I've ever seen. "No disk space", when my drive is basically empty. :wtf:
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For anyone using non 16:9 resolutions, like 16:10 or 21:9, who wants to have their HUD display in the correct place:
Go to your C:\Users\Documents\The Witcher 3\ and edit user.settings with notepad
Find the line uiVerticalFrameScale=1
I set mine to uiVerticalFrameScale=1.11 and the hud is now in the right place. YMMV. Remember not to click on Rescale HUD or it might set it back to the default 16:9 hud ratio.