After having just finished Dark Fall 1 & 2, which I really liked, I started playing 3. I'm not going to finish it.
First of all, the setting. it's the same as the 1st game, even including the same 'villain', it seems, but very clearly an entirely new universe. So many details have changed, and the first game story clearly had it so that the whole site would be renovated and/or rebuilt soon. This clearly didn't happen here. Really immersion breaking when at every new area something is just "wrong". Wrong place, wrong details, things competely out of place, things missing, etc...
Movement. So slow now! The new 3D world is niceish, but it means that transitions between sections are so much slower. No longer just instantlly moving, you slowly turn, you slowly walk forward. Ugh.
And finally, what really killed it for me is the addition of timed puzzles. I hate them. A lot. I was still figuring out a certain puzzle I came accross and suddenly game over. I'm returned to just before the puzzle, at least, but I quit and wrote this. Next step is to uninstall.