Skybox F5 Hd info request.

Hi guys, I'm thinking of upgrading from my kryptview cable box to the new satellite Skybox F5 Hd, however I have a few questions such as do you have to be a Sky customer (I doubt it) but thought I would ask the question. My second question is does the F5 box have the same troubles as kryptview (freezing glitches) etc.

Thanks for any info..