Talos really wasn't that hard. I wish it had fewer, but more innovative puzzles. You can only do the Tower of Hanoi sequence so many times.
Without wanting to disrespect Talos, what The Witness does with its chosen puzzle type is so much smarter and already more varied in a shorter amount of time compared to what Croteam packed into Talos.
While Talos showed numerous variants of leapfrogging-style puzzles (Tower of Hanoi), it really feels like The Witness is going
deep on its line puzzles. I think this is what it means to really explore a design space and get everything possible out of a certain puzzle type while also marrying it to some bigger puzzle ideas outside of the panels.
Talos was good, but from what I've seen of The Witness so far, it truly is something special.