I was really rooting for SlingTV. I'm very happy with the ChannelMaster DVR+ for watching and recording local, over the air channels. So I was hoping the Sling TV would be an inexpensive way to fill in a few of the cable only channels that I still enjoy.
The best I can say is that Sling is almost there. It has a great price and reasonable selection of content at $20/month, but it's not a replacement for the convenience of cable. I'll break my opinion into 3 sections, Picture quality and performance, user interface, and content.
For those of you that don't care about the details, here's the bottom line. I'm glad I tried Sling, but it doesn't fit my requirements. I'll be canceling when the trial ends. I wouldn't tell you not to try it. Sling might fit your needs. Make sure you have relatively new equipment, a decent home network and Internet service, and can live with the inconsistencies I describe below.
Picture Quality and Performance.
Using Netflix as a standard of comparison, I got the best results when viewing with a Roku 3, the ChannelMaster's SlingTV channel or my laptop computer. Just as good as Netflix. But, in order to maintain that level of performance I had to restart my router every 2 or 3 days. Normally, I would only do this every couple of weeks regardless of my home network performance.
On the smaller screens of a tablet or phone, quality was acceptable with minor dropouts and buffering. Nothing too annoying.
Sadly, when viewing with an older Roku 2 or a ChromeCast picture quality was poor. The resolution was seldom high enough to read text and the stream suffered frequent buffering. As a test, I would immediatly switch to Netflix. In each case Netflix, Amazon Prime, and MLB-TV would work fine. It's pretty obvious the problem is with Sling.
So, with the newest devices I had reasonably good results, but frequent router restarts were necessary.
User Interface -
Sling attempts to use the same basic interface on all devices. I give them an A for effort. The user interface is OK when using a touchscreen or mouse. It's annoying when using a typical TV remote control. The best I can say is UBF. Ugly But Functional. UPDATE: July 2016 - The Sling UI for Roku has been significantly redesigned. It's still not great, but it's better. The addition of a way to designate Favorite channels and Shows makes it easier to quickly navigate to things you regularly watch.
The channel lineup isn't bad. It's delivered as described. Features are the problem. At a minimum, I expected to be able to pause and restart any show. Some channels give full control over Fast Forward, Rewind and Pause; other give no control at all. The size of the library of previous shows is also inconsistent. Some details follow.
Channel Feature Breakdown
UPDATE: July 2016 - I removed the detail that was previously listed here. Sling is in flux, with new channels, features and offerings. I'll just say that the features and number of past shows available vary by channel. Some channels will let you have full control of pause, fast forward and rewind, others have no control and still others have a subset of controls. It's similar with the library of previous episodes. Some channels have a lot, others have very few. You'll have to make use of the trial period and check the channels that are of interest to you.
There you have it. Overall, it's close to what I want, but not quite there. If I had full control (or at least pause) the live stream, and each channel had a library of at least the last couple of days of shows, it would have been a hit.