Bought and finished Talos Principle: Road to Gehenna over the weekend after really enjoying the main game shortly before..
Would have been nice to have a new mechanic (actually cut out the platform as well), but the puzzles maintained their quality, the story/themes were interesting and the message board delivery was pretty amusing having been around them for so long. My only real issue with either game was that the majority of the times I got stuck for more than a few minutes turned out to not really be logic failings but either not understanding a somewhat arbitrary mechanic (you can only elevate something by placing a box on an unpowered fan and using that as the base for example) or that I had just missed a hard to see item for a few minutes (the first platform..). Something like Portal 2 goes the extra mile with visual cues and dialog to explain all the mechanics clearly, while still being challenging in the actual logic of puzzles.
Also didn't like the implementation of challenge stars, which going by the message board dialog in Gehenna others didn't as well. If I knew which puzzles required items from other puzzles (they make you find jumps to get over gates that prevent you bringing items in/out), I would have skipped those and done the others. But as is, I had to skip almost all of them in the original game because otherwise I was risking spending half an hour thinking I'm close to solving a difficult puzzle when in reality it was impossible with the tools on hand. After doing so once in Gehenna (you need some stars to unlock the final level), I just opened a guide and tried to skim it to see what was necessary but leave the puzzle bits to me.
But only really mentioning the issues I had because it was otherwise so satisfying and thoughtful, definitely a high recommend. Might finally give Antimatter a shot while I'm in a first person puzzle mode.