One nice thing about the new look is that it's somewhat customizable, i.e. message list density. Along with a few choice Gmail Labs projects (or Greasemonkey scripts, if you must), Gmail can be almost whatever you want it to be.
I recently discovered the "split pane with preview" Labs option that makes it very much like a desktop email client and it's pretty interesting! I long ago got used to not having the preview pane, and I don't like everything about the behavior when it's enabled, but the quick toggle and easy switch between vertical and horizontal split is pretty cool. I haven't yet decided if I'll end up using it enough to leave it enabled but it's awesome to have the option.