I've just joined up to the Online version for the three month offer after my schedule meant I cant get to my usual class any more. It works out about £5 a week and there's no difference in what you can access online compared to what you get with your PIN on the group version.
I had considered just trying to do it myself but what made me sign up was having an official register of my weight (the graph etc showing me how much I had/hadn't lost) and access to the syns calculator.
I dont think Ill stay on after the 3 month renewal thing, but Im not totally sure. To be honest you can get graphs free online anywhere these days, like this Ticker thing, so it's only the Syns calculator I want and you can find out most things through chatting to people on here. At the moment I probably wouldn't sign up again, I think a fiver for a syns calculator is a rip off (although apparently you get a reduction after the 3 months is up, Im not sure how much).
I think nothing compares to a good group class, (unfortunately I dont have access to a good one any more) - but this forum seems pretty good (and free) substitute.