Yes. I have also attempted to do the five square one - four on the corners which intersect into the one at the center. HARD from the Sunday Washington Post)!! And I have attempted to do the one based on 16 rather than 9. Again, very HARD. This one also asks for 1 thru 16 diagonally both ways causing an X. I copy this one and enlarge and attempt it several times before giving up. But it is great mind exercise regardless.
I also do KenKen. Anyone doing this one? It is a daily.