Where are you based in Thanet? If you have a good line of sight to the Staner Flats (Manston Tesco area) you should get a perfect service.
I've been with VFast (previously So Broadband) since I can remember and since VFast have taken over I can't say I've had too many issues, especially since I was upgraded to the new network last year. I was on a trial service at the end of the year/beginning of this and I was seeing speeds of up to 50mbit - http://youtu.be/RaDq38vm6Zo.
So it gives you an idea of the speeds that you can potentially get, there was also talk of 100mbit services but VFast have gone quite on this for now...
Unfortunately I'm having some speed related issues at the moment but support (Jonathan) is looking into the issues for me, but it could be down to the fact my LOS isn't the best due to trees and the foliage. I'll have to see after some further testing. Hopefully I'll be back to full speed in the near future, perhaps when we hit Autumn... lol.
I wouldn't say £25 is expensive especially when you're getting 15/2mbit speeds, unlimited downloads, great support, all when you can't get a decent ADSL/Fibre connection. I personally think it will be even better value when we get speed upgrades in the future....... hint hint... ;o)
VFast Wireless Broadband.