No catch. Confirmed no traffic management, no download limit, free router, free migration. This is purely for customer retention.
I'm 800m away from the exchange and get 12.2Mbits down and 1.1Mbits up.
I pull an average of 120Gb/month over the line with no problems.
Edit: just to add I was paying £35.50/month with O2 before which is crazy amounts.
I was on o2 for 3-4 years before being transferred over to Sky last month. Since transferring, I've had nothing but problems. Online gaming pings have gone from 20 -> 50, download speeds have fallen 20-30%, my connection frequently hangs (Youtube is near unusable), and I now have issues loading websites from time to time (I had to refresh Google 3 times before it loaded earlier). To make things worse, Sky is charging me £15.50 a month while o2 was only charging £7.50.
Thankfully, BT is installing fibre in my area so I should be able to jump over to plus.net sometime soon. I can't wait.
I'm in London and my exchange has Sky LLU support. Coincidentally I live in the same postcode as Sky HQ so any problems, I'll talk face to face with them as I have some contacts.
I'm not trapped by a 12 month contract, which is why I'm not too annoyed about the situation. My cabinet will get fibre fitted early next month, so I should only have to endure Sky for another month or two thankfully, which is ok by me.
For many users (especially your average home/family users with less technical requirements, not using it for critical purposes such as home working) they're probably perfectly adequate.
FWIW, I use BT's (formerly British Telecom) FTTC Infinity for Business product. 78Mbps down, 20Mbps up, worst case 1:20 contention, no caps or allowance-related FUP. Their customer care and technical teams are pretty decent. And I can get a /29 in addition to the dynamic PPP IP for the WAN link. Where I am (NE Scotland), BT own all of the widely available (non-private) infrastructure so it's easier to deal with a single company in the event of a failure vs being pushed between ISP and infrastructure provider. YMMV.
EDIT: FYI I pay £45 ex VAT (~AUD 102).
I treat my home connection like a coffee shop's WiFi.
The real meat and two veg of my setup is a hosted desktop I RDP into and a number of hosted Linux machines.