I've been using PageStream on the Amiga since version 2.0. I have 4.1.x.x (4.1.4.0 installed, 4.1.5.6 in an archive) on my Amiga, and 4.1.3.4 on my Mac.
On the Amiga, it follows the Amiga Inteface Styleguide as much as possible.
It does the same on the Mac (Mac guidelines), and I would guess the same for Windows and Linux as well.