There is a fair usage policy of about 15gb, I'm a little worried about that but to be honest I don't use anywhere near that currently but may do with better speed....i suspect they may revisit this as they have just increased speeds and offer 20mb with a soon to be 50mb
Cost wise there is a range of packages,
http://www.ineedbroadband.co.uk/home_level.htm is the best place to see them but I am going to try out 8Mb for £25.50 (raises to 28.50 in 3 mths) but will also add in VoIP for £5 a month. Currently pay talktalk £6.50 for broadband and £14.50 for line rental, we probably spend £6 a month on calls not included as Parton package which will either be free (for 01.02,03 numbers) or 5p a min for mobiles so should save a bit there, on estimates if it all works as promised I should be only paying a couple of extra quid for potentially faster and more reliable Internet.......... But being a sceptic I will keep talktalk running for a few weeks alongside the new install so can revert back if any issues crop up.
Sorry just realised that didn't quite the question as am using the iPad app, this was in reply to autos post a couple above :-)