When comparing SteamOS vs Slackware, the Slant community recommends Slackware for most people. In the question“What are the best Linux distributions for desktops?” Slackware is ranked 23rd while SteamOS is ranked 39th.
Ranked in these QuestionsQuestion Ranking
Pro Native graphics processor support
The OS natively supports Nvidia, Intel, and AMD graphics processors.
Pro Streaming service integration (under development)
Valve is in talks with streaming companies such as Spotify and Netflix to bring their features to SteamOS.
Pro For entertainment, it just works
What media center software do for videos, it does for games (and later videos).
Pro Ideal to learn more of Linux
Pro Package management
Uses standard tar archives with shell scripting as packages.
Pro One more distro which is init based
Some users don't like to install systemd based distros because they increase booting and processing speed.
Uses stable, plain-vanilla packages from upstream.
Pro Strong adherence to UNIX Principals
Pro No systemd
Con Not built around the desktop experience
SteamOS is, first and foremost, meant to act as a gaming console - it doesn't ship with even some of the most basic applications, such as a file manager or image viewer. As a result, using SteamOS as your primary operating system would require a fair bit of work.
Con Hard to install
If you've installed Arch you're probably fine, but for those used to simple installs like (Ubuntu to name just one) you should prepare some patience, determination, and painkillers. Good news is, it's getting better (it's very young).
Con Not User Friendly
Con Large size live ISO
One need to vain 3GB+ data for downloading one slackware ISO.