It's good, but not great, and sometimes it can be very annoying.
Why it's good: you get a bunch of sports channels and then a couple of other relatively cool channels (like AMC and TBS) for relatively cheap.
Why it's not great: because sometimes it can be very annoying.
Why it's sometimes very annoying: because the signal will cut in and out on you periodically, and sometimes channels won't even load. Like, for instance, last night we all sat down to watch The Walking Dead - a big perk for us, since we love that show. However, the channel wouldn't load. Nope, just frozen, can't open the AMC channel, so we are just sitting there hopelessly/angrily watching a blank screen while we are sure the show has already started. That has happened probably 10 times over the past two months or so that I have had it when it really annoyed me. (It probably happened twice that many times, but I didn't care that much to be annoyed by it.) Obviously, if my kids are full-on iPad streaming mode and the wife is full-on Instragram/FB/whatever mode, then that will cause some disruption to the quality/stream. However, even with everyone in the household off of devices, it still periodically freezes up (like it did last night with TWD).
Overall: try it out, see if you can live with the annoyances, and go from there. They offer a free trial period, and that gives you plenty of time to try it out and see if it's going to work for you. I know Sling TV got some bad reviews, which were kind of in line with my criticisms: it's great when it works, but it doesn't always work like it should.
Bonus: you can watch Sling TV on your mobile device, which is cool, as I can stream The Bourne Identity as I'm sitting in the airport in Atlanta.