In general it`s a good package. Until early April I was on a 24/7 Broadband coupled with 24/7 telephone and it was OK, somewhat cheaper overall than paying BT for all my calls. However, your bill can go up a fair amount if you rely a lot on phoning 0870/0845 numbers. I aimed for about £5 to £8 a month with these numbers and my bill worked out at an average of £26 a month. That paid my phone and Broadband. Don`t forget you`ll still pay BT for the line rental.
Only downside to these deals is Tiscali customer service. It`s hideous and well documented here on this forum. But then again, most BB providers leave a lo to be desired in the customer services part of their business.
Good luck, whatever you do.