I don't know about your brother's experience but I tried Sling for 3 months to get the free roku. It was pretty terrible. Lots of interruptions and hours of it not working. Forget about if it's a premier of Walking Dead or big football game. The service would go down on all channels. I canceled it as soon as I could. Not worth the aggravation.
I recently subscribed to SlingTV (using Xbox) and it's incredible. Probably watched it a good 20+ hours and not had a single issue. The playback is smoother than cable tv, no interruptions, no freezing, thus far flawless. I did hear it was horrible, early on when it came out. But from my experience of using it the last few days, they seemed to have fixed all the bugs and glitches.