I've been with Sky Internet since it was launched (couple of years ago). I have no problems except a minor one in the first week.
Since then it has been faultless, getting better speeds than previous (Nildram) at 1/5 of the price.
It is operated by EasyNet, not Sky and they are pretty competetent.
But here are some health warnings ....
1 - If things do go wrong you have to deal with Sky on 1st line. They are not very good and their usual patronising style. It takes a bit of work to get put through to an engineer but then you are speaking to EasyNet and everything is fine. So if you aren't confident at arguing your expertise and knowledge it could get frustrating.
2 - You have to use their router (actually you don't, see later) but it's free and a reasonable netgear model. It has modified firmware so you can't get at your assigned username and password.
It is actually a good idea from a support point of view because everyone is on the same router. Sky can apply patches remotely and can talk non-IT literate people (like my mum) through problems.
You can get at the username and password using HTML injection - well documented on the forums and then you can use whatever router you want.
I've done this but still use the Sky router - it was free and works well enough.
There are 3 price bands
Free
Mid (£5)
Max (£10)
Unless you are a light user I would discount the Free one. Unless you are a very heavy user or have very good line stats you won't benefit from Max. So go with Mid. Sky are always happy for you to move up but not down.
Cheers,
Nigel