The break out box can accept HD sources at 720p or 1080i, though not 1080p. It connects to what looks like an HDMI port, but in fact it's just a proprietary port, which could cause some confusion as some might try and hook up an HDMI connector directly to it. One limitation I should mention straight away is that this does not mean you can stream in HD resolution - the maximum is 640 x 480, though the top bit-rate that the Slingbox can process has now increased to 8Mbs, which should provide a good boost in quality.
If you want or need to use a SCART connector then you get an adapter, which will convert you SCART plug into a composite output, while still enabling you to pass through your SCART plug to whatever it was originally connected to, which is good. Unfortunately, you won't be able to get an RGB signal from a SCART output into the Slingbox, it's composite only, which means you'll need to drop down slightly in quality to S-Video unless your source has a component input. All the inputs now have pass throughs too, so you don't have to disconnect them from the outputs they were previously connected to. The larger size of the Pro means that the Slingbox now has room for full size phono audio connectors, which should make installation in an AV system a little easier.
There are two small lights on the Slingbox, one which tells you've got power, and the other when you're connected to the network. It should be a solid light for both but for some reason at first I got a flashing light on my network connection. However, holding down the reset button cleared the error, and all was well.
One thing you won't find in the box is a software CD. Sling Media updates the software frequently and it makes sense to make punters just download it when they set up. A wizard picks up the Slingbox on your network and the first time you'll be asked to give it an individual name, and create a password to access it, and another one to set up an administrator account who can make changes to the set-up. Assuming you've plugged in everything where it should be you should straight away see a picture in the wizard from your source. You then tell the software what the source is, and the chances are that full remote control codes for it will appear in Sling Media database. After this, the Sling Player software will show a virtual version of the remote with pressable buttons so you can control the source as if you were in the same room. For something like a Sky + box you'll get an exact virtual replica, but for something a little less ubiquitous you'll get a generic remote.