I'm personally not too much of a fan of the current OS X-esque styling, so I'll be mocking up a newer, lighter, flatter style for several apps over the next few days. The goal is to keep the current layouts and HIG, while offering a less Apple-y look.
Hm- the grouping of the maximize and 'hamburger' menu button seems to imply that the menu serves a similar function or has a purpose on the same level as maximize/fullscreen. Of course, it is quite different. According to the HIG, it would make sense to put the menu further in, since people probably maximize more often. Also, the level of padding between the buttons and the window border is debatable. One idea could be to have the buttons lay flat against the side of the window, making them look more distinct (and possibly being a better target area for the mouse when the window is maximized).
I like the style- it almost reminds me of where GNOME is going, but a bit more toned down. It's good to see that the title and toolbar are obvious, but not overpowering the content. I could live with this, certainly.