It changes Steam to a newer look, with a clean interface, a professional looking font, and the colors of your choice.
This skin is designed to fit in well with the default Windows 10 look, making for an app that will fit in well for those that are worried about aesthetics.
There is an optional third party app available for this theme that will allow users to change the color settings of the theme as well as fonts and a few other settings.
Whatever action not displayed in the main window area, gets shuffled into one long list hidden under the hamburger menu.
It doesn't lag and it feels very smooth compared to other skins.
The last update for the skin was in October 2015, while it may not need many updates for bug fixes it would be nice to see continued development.
You can find the patch here: https://github.com/redsigma/UPMetroSkin/
This skin has Aero bars and looks more tidy than default steam.
While the dev has discontinued development the skin is available to anyone who want to continue, meaning that while it is abandoned someone else may pick it up.
What is available is the final version, if any Steam updates break the skin there will be no fixes.
Being that this skin is developed by one person who is new to theming the skin is only available on the Windows platform, so those using the Linux or OSX Steam client are out of luck.
Words are made more prominent and placed in ideal areas in order to make the client a bit easier to use.
Placement of elements and other design looks integrated as a whole.
The design, albeit similar at a glance to the default Steam skin, actually changed quite a lot of aspects giving a fresh new look to the Steam client.
Users have noticed clipping of fonts as well as jumbled areas where fonts and icons mix. Due to how Steam updates its looks on its own there is always a risk of issue if fonts or other UI elements are changed. Sadly it does not look like the dev is keeping up with these changes, which is why fonts are clipping.
If you don't like a certain aspect of the skin, for instance, the "green fog" that covers the background of a game's detail screen, you have to manually edit the values.
The skin seems to have lag issues. This is a known bug.
Air Skin features light blue backgrounds/borders and white text. There's no harsh or noisy colors.