Unlike Qt4, Qt5 doesn't come with a configuration tool to allow setting the icon theme, fonts or the style and instead, it tries to use the settings from the running desktop environment.

This works well for KDE and GNOME (as well as Unity) but you may encounter issues under other desktop environments such as Xfce, Cinnamon, MATE and others (I'm not sure what Qt5 versions are affected by this, but it seems to be fixed in the latest Qt 5.5.1 according to THIS comment).

Here's an example (Audacious 3.7 using the Qt5 interface under Linux Mint 17.2 with Cinnamon):

Yarock 1.1.3 was released recently with a new radio service: Radionomy (which has replaced Shoutcast), support for importing APE files in the playqueue, MP4 audio tag reading and more.

As we pointed out a while back, the Audacious developers aren't very happy  with GTK3 and for the latest Audacious 3.6 alpha 1, released recently, they've switched back to GTK2 by default. 

Also, since the long-term goal is to completely switch to Qt, Audacious 3.6 alpha 1 includes a new Qt5-based user interface which is already usable, but not as feature-rich as the GTK+ interface. The new Qt interface can be installed alongside the already existing GTK+ and Winamp Classic interfaces.

According to a recent announcement, Ubuntu will use its own Display Server called Mir, replacing X Window server. The reason Ubuntu will use its own display server is that "none of the existing solutions would allow us to implement our vision without taking major compromises which would come at the cost of user experience and quality" and obviously, to achieve full "convergence", a hot topic recently that has caused quite a bit of controversy.

Besides supporting most popular image formats like gif, jpeg, png, bmp, tiff, xpm and so on, Photo can also perform some basic image manipulation like rotating, flipping or zooming, display exif information and comes with a beautiful interface. When opening an image, you can quickly switch to another image in the same folder by using the thumbnails displayed at the bottom:

Razor Qt is a lightweight desktop environment - think of it as LXDE, but using Qt. It doesn't come with its own window manager and its developers recommend using it with Openbox, but it should work with any window manager like Kwin, Metacity, etc.

Razor Qt 0.5.0 has been released yesterday, bringing lots of new features and performance improvements. For instance, there's a new appearance GUI for configuring themes:

The new version brings 3 new components: razor-policykit, razor-power (power management tool) and razor-autosuspend (a tool to suspend/wake-up laptops on Lid events or power status events) as well as some panel improvements:

YaRock is a very simple music player for Linux written in Qt (it doesn't install KDE libraries so it can be used under GNOME without KDE services, unlike Amarok for instance) that doesn't have many features for now, but what's very cool about it is the multiple views: album, artist, track, genre, year view or folder view. Every part of the UI is very well though which makes YaRock a pleasure to use.

The default Unity ("Unity 3D") has a cool workspace switcher that wasn't available in Unity 2D (Qt) until last night's updates. Check out the video below to see it in action: