I tried Sling for a month in 2016 on a Windows computer, and I promptly cancelled after that month. While watching a program, the transmission would stop and the following error message would appear on my computer monitor: "Due to inactivity, playback was stopped to save bandwidth." When I first reported the problem to Sling tech support, they replied with a bunch of canned paragraphs which had nothing to do with my problem. When I wrote back asking for a better response, they replied with "I apologize for the previous response. There is no way currently to remove the "inactivity" trigger (outside of pressing a button on your remote every once in a while). I can be sure to put in a request to have the feature removed."
Since I was using Sling on a computer, pressing a button on a remote wasn't an option. Essentially, the interrupted transmission meant that I was being punished for watching an extended-length program (3 hours or longer). That limitation resulted in many programs (e.g., most sporting events, coverage of breaking news stories, epic movies, etc.) being cut off before the end. In addition to the technical problems, there was no DVR feature on Sling at that time.
The author's comment "While apps for PlayStation 4 and web browsers would be nice, Sling TV is probably the most widely available cable replacement at present, and it could still expand in the future" doesn't make any sense. First, Sony has a competing service (PS Vue), so it's hardly likely that an app will be developed to watch Sling on a PS4 game console. Second, it's stated elsewhere in the article that Sling already works on Windows and Mac, so browser support is currently available. Third, PS Vue went national in March 2016, so the claim that Sling is the most widely available service probably isn't true.