It is indeed fast.
It was 40mpbs faster when I checked yesterday, but that's still much faster than it takes to render many web sites once their content has downloaded. For ones such as those of the BBC, that are on sites with a lot of broadband that don't pack their sites with tons of garbage that the browser has to sort out, they appear pretty well instantly.
I had two connections I was using before this. The fast-but-unreliable one that used microwaves or something gave 62mbps (as of a minute ago). The slow-but-reliable BT connection over copper cable gave no more than 1.7mbps. My 900mbps+ fibre connection is therefore definitely something of an upgrade.
I'll see how it goes for a couple of weeks, and if there's nothing amiss about it then I'll cancel my over-the-airwaves contract.
This is going to make downloading new games much easier!