I was on one of the original 5 trial exchanges a years or so back (albeit with a different ISP – my employer, so got it free).
It is ultimately still a copper product*, so you will get speed variations between users.
If BT are offering it, then any other ISP at your exchange will likely offer it too. So, if you’re with someone else, you may be able to get it at a good price to remain with them (e.g. TalkTalk – it’s not actively sold, but is available).
*Fibre from the exchange to the green cabinet in the street. Copper from the green cabinet to your house.