£1 off per month doesn't seem very much to me at all. You haven't even said how long the contract is, or what setup fee they charge. Looking at the link you gave TT seem to be hiding that very well!
Also, there is plenty of information on the net about how diabolical their customer service is.
Don't you think you should warn members about that?
I have read of them repeatedly charging for calls not actually made on their telephone service, and then blocking the account if a customer complains and doesn't pay up straight away.
I should say don't touch, not even with a long barge pole!