I've considered switching from Windows 7 (not upgrading to 10) but is it worth the switch and are there any major issues in using it as my main OS?
SteamOS is a Debian based Linux distribution so If you plan on using it as a main OS I'd recommend just going with another Debian based distribution as it'll likely be more stable than SteamOS and have much better community support if something goes wrong on your system.
I recommend mint it's a nice home
Mint is a very good choice, so is Ubuntu or any of its derivatives or even just standard Debian.
+1
@avgnfan26 If it's your first time using a Linux distro, I reccomend a dual boot setup (Win 7 + whatever Linux distro you choose); also note that not every game you might have in your steam library can be played on Linux.
This, I have 128 out of 275 games in my Steam library that will run on Linux/SteamOS and most of them are indie games which isn't necessarily a bad thing because most of them are awesome but just don't expect most AAA games to work.
I don't think steamOS is a good choice for a desktop operating system. It's really made for dedicated gaming machines hooked to a TV. You can install steam on whatever version of linux you like and it has the exact same functionality.
I'm going to recommend manjaro, it's really easy to install the graphics card drivers and you can install steam from the package manger without any trouble.
I second Mint. Steam OS is designed for gaming machines and smart TVs and such. Underneath is basically Debian which is brilliant, stable and has good documentation but not tailored made for new users.
Mint is a good transition from win 7 and Steam will work exactly the same way as it would on SteamOS. Dual boot is a nice solution. You just keep a Win partition for games you cannot play on Linux and you do nothing else on it. It will probably perform better too as it will be much cleaner.
I will also recommend something else as a daily driver then SteamOS.
people are saying mint here that will probably be good or ubuntu :P
if you run into problems hop onto the teklinux channel on efnet and there will probably be someone/someones to give you a hand.