[I wrote this on Google+, but decided it should probably exist, in a revised version, here too]
I remember hearing about Promise TV several years ago at Open Tech 2005, so it's nice to see that there's a real product now available to buy.
In essence they've built a Freeview recorder that records every programme on every Freeview channel, and keeps it for a seven day period before replacing them. In other words, every programme aired has been recorded whether you remember to record it or not.
I suppose in an age of iPlayer/4OD/ITVplayer, having your own personal recording becomes less necessary. Just stream the programme you missed! But then you can't save something on iPlayer for later beyond the 7 day window. Nor can you put a stream on your non-connected portable media device without significant DRM issues. And if it's a film or sporting event, rights reasons may prevent the programme being included in the channel's streaming offering (the website doesn't seem to explicitly say you can move media off the device, but I'd hope you can).
So in that regard, this seems like a fascinating idea.
And they've included radio which is very nice!
I'm not sure how many TB of disk space they have on the machines. The specifications don't make it clear. But assuming that it's recording in a native MPEG 2 format, that's likely to be somewhere around 2GB per hour. That's a third of a TB per channel for a full week. I think we can assume that there are a handful of 1 or 2 TB hard drives built into each unit.
The only disappointment is the price - £1200 for the "Lite" 3 day version. That puts it in the "enthusiast" marketplace rather than consumer one. Certainly it's beyond my price point. But I guess that at least half that cost is due to the hard drive requirements.
I can see this being a very sensible purchase for a lot of corporate marketing and PR departments. There are some quite pricey companies who offer a service based around them archiving output from the major TV channels. They charge clients to access clips of shows that may be of interest to them. For a one-off payment, a company that regularly uses such services could buy a Promise TV device itself and as long as most of the clips they want are from within the seven day window, they could clip them themselves. The Promise Pro seems to offer this facility.