Is that a good deal to redeem the games here afterwards?
For me, they are €11.26. Current price for the full package on GOG is €45.77 (or €36.77 if you buy them all together), which makes the €11.26 price about a 75% discount. Having said that, there are two things to keep in mind:
1) They need to be redeemed on Steam first, in order to retrieve the retail key embedded in their library entries.
2) As has been mentioned by quite a few users in the respective thread, there is no 100% guarantee that the keys will work.