I've never noticed slow speeds, and speedtests always show almost exactly my sync speeds. On the few times I've contacted support by email I get almost instant replies with good answers. I've had one short outage in 4 years, which was Openreach's fault (obviously!) and got resolved within an hour or so.
I like that they don't give you a router and let you use your own equipment, I like the static IP for home use, and I like the payment for a year upfront to save a bit. The customer portal is easy to use (not that I have much need for it, as it's an unlimited connection).
I've used them for a few years, first on 80/20 fttc and now on 160/30 g.fast. Maybe they're not as cheap as plusnet, but you get what you pay for.
Time With Provider: 4 Years
Package Name: G.fast 160/30