I don't have enough expertise in design to articulate why, but it seems to fall quite short of `cleaner and more modern.' Well, maybe it is a bit less '90s than the previous design, but I'd hardly call it clean and modern. The logo off to the left of the banner is odd, the different fonts and sizes aren't pleasing together, the columns of links seem like something you'd see at the bottom of a page rather than in the middle -- I could go on.
I wouldn't call it `cleaner and more modern' either but I really don't care. The best thing in Debian is that you don't have to visit their website often (or at all), because everything works in it, and everything works from command line.
All of the main "volunteer" Linux distribution websites are terrible in terms of design. Gentoo, Slackware, CentOS (ugh!) and Debian all leave a great deal to be desired. Every time I visit the CentOS homepages and have to navigate their ugly menu, I die a little inside.
Sorry to call someone's baby ugly. Is it just me?