The most noticeable change in this release [theregister.co.uk] – the only visual change, really – involve the scrollbars. Yes, scrollbars. Canonical's homegrown versions have been ditched in favor of the GNOME scrollbars in GTK 3 applications (which accounts for the majority of Ubuntu apps).
The GNOME scrollbars have been themed a little to look like Ubuntu's old version, but the strange, handle-like thing is gone. The move seems primarily a result of the fact GNOME's scrollbars more or less now behave just like Unity's did. In other words, there's no need to duplicate scrollbar efforts.
The annoying thing is that while the behaviour of the scrollbars has changed, all the bad UI decisions remain – which is to say that even when there's scrollable content, Unity will still not show a scrollbar until either you hover the scrollbar or otherwise put the mouse in motion. How do you know there's scrollable content? Well, your guess is as good as mine. At least now Canonical engineers can move on to something more exciting than maintaining homegrown scrollbars, though.