I bought and installed one a few weeks ago. The video freezes for upwards of 5 to 10 seconds occasionally, but audio stream flows fine and uninterrupted. ... the speed of your internet connections obviously play a role in this.
It isn't perfect, but I'm very happy with it.
My Slingbox is connected to a cablebox/DVR ... and I'm able to control this cablebox/DVR unit from afar. It's pretty cool.
The initial hook-up went o.k. I went through the various steps, hit a snag, initiated a helpchat (via the Slingbox website), the technician completed the installation remotely, and I was good to go.