I'm with them the now, my 18 months finishes next week and I'm leaving due to some issues.
Router: The one they provide is inconsistent in its performance and to be honest its a bit pants looking and you can only use that unit with their service.
WiFi: Oddly drops and sometimes you have to force a device back onto the service at times, also a few times it has forgotten items and I've had to re-add them.
Data service drops: Sites unreachable at times, support unwilling to listen when I provided documented evidence from their own router ping tests. I suspect issues with the internal network as addresses were not resolving IP's and when testing return times I could get a IP address to be far more consistent and lower in its return time. I did change the DNS servers but no change in performance, it was very very random when it happened over the last 4 months.
Service: Twitch and streaming sites have degraded performance a times, they simply just stop streaming data to my devices (Traffic shaping maybe?) at times.
Email: No service option for the cost
Cost: I'm still paying for line rental as they are uninterested in making sure the customer is getting the best deal (Might have renewed my contract with them when this change happened last year), but hey I'm not all that surprised since most UK companies treat existing customers
I'm looking at iDNET and possibly their gaming version, very expensive but prio is gaming and the likes of twitch/streaming.