It all depends on your internet connection both where your slingbox is located, and where you're watching your slingbox.
If you have a great internet connection, you're going to have a good time. If your internet connection is shoddy, it's going to be less fun.
Also, when you're using your slingbox, the cable box that the slingbox is hooked up to cannot be used by anyone in the location where the slingbox is. Well, they can use it, they just have to want to be watching what you're watching. Does that make sense? Basically, if you're watching the Rangers in DC on the slingbox, and someone in NJ goes over to the television that the slingbox is hooked up to and decides to watch Honey Boo Boo, you will be watching Honey Boo Boo as well. (I hope this paragraph makes sense).
I used a slingbox my entire freshman year at UB while dorming, and it was fantastic because the internet allowed it to be. When I moved off campus, however, it was a completely different story and led to me purchasing Center Ice because the feed was so terrible due to the internet.
Hope that helps!