Well any box will only receive whats being broadcast; but you will get every channel thats on a "chipped" pace/samsung box, PLUS a few test channels, PLUS some vod events (not even worth bothering with), PLUS you get to try out new channels BEFORE they are released on the official cable lineup.
For example, dreambox users were watching Sky Movies 9 and 10 several weeks before it even started to appear on the original cable boxes. And it was the same with the Horror Channels and Sky Two, etc.
So as a general rule you don't really get any extra channels on a dreambox because a box can only ever receive whats being broadcast by the cable company; but you do get the added extras of "sneak previews'" of channels and sometimes the big VOD sport events (if people order it in your area).
But a dreambox can do so much more than just watch TV and if you did eventually get one then you would be constantly tinkering with it; its not just a cable box its a linux multimedia terminal and can record/stream and interact with your PC and network.
Dizzy