There's about 20 new puzzles, plus some tweaks to existing puzzles.
There's several new body parts to build your contestant with: a couple new bodies, some more eyes, and a new mouth.
The game now detects the size of your display, and offers whatever window sizes it can that will fit. (Users of 4k monitors no longer have to suffer with tiny windows!)
There's now a CRT option, for those of us who somehow have fond memories of 50-60 pound monitors :P