But its not all that competitive when I read the package from Sky which includes TV as well. In fact I pay £20 for broadband alone which these days is expensive. Any views?

Obviously, Sky is only a good deal if you are going to make a lot of use of the television.  Personally, I think it is a waste of money as the programmes are all repeats and full of adverts.  Of course, it is a different matter if you pay for the sports channels. 
You have to pay for BT line rental on top of the call package as they are not doing line rental just yet ASFAIK.  This makes the call package more expensive than the PN one. For the free broadband I understand that it is restricted to 2MB.  My friend across the road has it and her BB is markedly slower than mine (5MB).

@poppy

They now do line rental - see here

@Evilgenius

Poppy is right - broadband is only "free" for up to 2Mb (with a 2GB usage cap) Also note this "One-off £60 set-up cost for existing customers" on this page.  If you want faster speeds it costs £5 extra for up to 8Mb and £10 extra for up to 16Mb (with reduced set-up costs)

They've also just increased the prices for 0845 and 0870 numbers to 6p/min at all times for 0845 and  to 10p/min in the daytime and 8p/min in the evening for 0870 (compared to 2p/min daytime, 0.5p/min evening for 0845 and 6p/min daytime and 1.5p/min evening for 0870 with PN).  Their connection charge is also 7p per call for non-inclusive calls (PN's is 4.5p, BT's is 6p).

Sky have also increased a lot of other charges - see here.

Remember that the package prices quoted don't include line rental (either BT's or Sky's) so you'd have to factor in another £10.50 for BT line rental or £10 for Sky line rental.

Therefore, assuming you wanted an "up to" 8Mb broadband package with all 6 mixes on the TV and evening and weekend calls it would cost:

Sky Line Rental £10
Six Mix £21 (pricing here)
Up to 8 Meg - £5 (pricing here)

Total = £36


Also note the standard set up costs at the foot of this page (in the notes).  £30 for new customers, up to £60 for existing customers.