looking at ispreview it looks like their once good customer service has taken a nose dive and is now quite poor.
IDnet are not an option on the cityfibre network for me
Vodafone
TalkTalk
Giganet
Zen
Brawband
Brillband
the first 2 i wouldn't touch with a barge pole.
i know nothing about giganet.
and brawband and brillband seem to be those ISPs that pop up with zero history and most likely just re-selling someone elses product.
If Giganet can't deliver over their own network or CityFibre they use ZenW over Open Reach. Seem to be a reasonably well regarded ISP as far as I can tell. I didn't go with them because I didn't want to get tied into a long contract over ZenW. I am paying IDNet £4 more for an 80/20 connection than Giganet would provide a 150/30 connection. I am not tied into IDNet though, which I felt justified the additional cost.
However none of that is pertinent if you have CityFibre available to you. There is a 3 month free offer to tempt you as well.