I would be interested in any info people may have as to whether such a large amount of whitespace does or does not improve user's understanding/use of sites. I like dense displays, but I'm also willing to learn how to use more powerful tools, as I value the efficiency.
I like the new layout and white space, it's much easier for me to read, but I've always liked this style. In fact, I have a tendency to double space much of my code and other coders hate that I do this.
The only think I REALLY don't like is the giant red COMPOSE button. Uhg. I just want to change it to another color. I REPLY all the time but don't compose often, and having this giant red eye-sore there all the time is very uncomfortable.
It definitely took me a bit to get used to a typography-centric layout. I really do like it now, however.
The increased whitespace makes it massively less dense.
The new buttons however are quite nice and simple. There should be a hint of 3D though, to make them feel more "press-able". Other than that, I am okay with them becoming wide spread on the web, just don't surround them with so much wasted space.