Recs.
Updated
Specs
Pros
Pro Steam sales
Steam has daily and weekend sales as well as publisher sales, though their biggest sales are their winter and summer sales. Steam is known for their deep discounts (discounts on games range from 10% to 95%) on games and has pushed many other stores to do the same seeing Amazon and other storefronts match their pricings when sales go up as well as hold their own seasonal sales.
Pro Cloud save games
Sharing save games between Mac and Windows machine is pretty nice though the game has to be a Steamworks game in order to have this feature.
Pro Fast downloads
Steam has excellent servers and their download speeds tend to be the best out of any digital store online.
Cons
Con Lots of DRM
Many games are not only Steam DRM protected but by another DRM system. It just cries for something to go wrong.
Con Little support for older titles
Many older titles (10-15 years or more) are no longer supported and thus require much manual tinkering to run properly on windows 10, requiring digging though forums and trying many things. Compare that to GoG where these titles often run out-of-the-box.
Con Buggy client on Linux with little customer support
Linux support is generally overlooked. It is recommended to disable in-game overlay and to use a real browser to interact with steampowered's website. Basic library access works usually without a hitch.
Also do not expect real tech support on Linux. Forum questions of bugs often go unattended and unanswered.
Con Pricey
AAA titles are very pricey, very often more expensive than at other online stores and sometimes brick & mortar ones.
Con Requires to log into Steam every 2 weeks
Steam forces you to periodically log into Steam Store every two weeks, or your games will stop working. They will force you to keep adding the API number, which is a pain. There is an Offline Mode, but you still have to log in at least once every two weeks.
Recommendations
Comments
Flagged Pros + Cons
Out of Date Pros + Cons
Pro Steam Greenlight
Steam Greenlight is a great way for indie developers to get their games on the market without a big Kickstarter campaign.