Ok so it's not going to be free but then they never said it was going to be free. Whatever the case, somewhere along the line you're going to have to pay for content and hopefully good content.
I'm saving in the region of £250 a year by stopping my Sky subscription (which incidently is the only option in my area and is the cheapest for Eurosport access). The only thing I really watch on the channels was Eurosport (and the occational Takashi's Castle
on a Friday night). The kids watch mainly the free channels. My wife is missing the UKTV Gold but appart from that there's very little that interests us as a family on Sky.
One good feature of SBK.TV is you can download the content. Looks like they will have the back catalog of races very soon as well (back to 1993)
I'm signed up so i'll let you know how it goes over the year. Next year looks like it will be £25 btw.