I have had nothing but problems with this. I got "conned" into taking a card out with the promise of the equivalent of two free flights and diamond club membership at the airport in November 2010 on the way to Israel. At the time I thought it would be great just to use the card to get the airmiles which would pay for Manchester to Heathrow should we be able to go again in the future. At the very least I could use them to go to London anyway.
Countless times my email/membership/password have never been recognised, and I have had to ring up to try and get it sorted. The first time was because I had set up the account manually, then found out like another poster has said, you get one set up for you with a welcome letter. They never told me this would happen. Eventually they merged the two accounts but even now I can't login again and am in the process of having a 'password reminder' sent again.
The one time I did manage to login in was for a return flight to Edinburgh but could I get one - not for 3 months! Unlike the normal Airmiles or Avios as it is now, there doesn't seem to be anywhere near the amount of decent availability unless you wait for weeks and weeks. At the time of writing this I am trying again to login to see if there is anything for Edinburgh but I don't hold out much hope at this short notice. I can see eventually I will have to plan to use them for maybe something I don't really want to use, just so they don't go to waste. The worry of that is if I am unable to go at the time as I have frequent health problems.