From a technical standpoint, the worst service I've ever used. As a small business, they will cost you money through service outages!
There are constant technical issues; migration from Microsoft to 123-Reg with no prior notice - which lost us functionality, email accounts not working - locking us out from accessing due invoices, not being able to add new users through the platform, to name a few.
When we were locked out of an email account, I followed up with the call centre, multiple emails, and chats, and was told that they couldn't do anything as it was a technical problem. With no idea of when it would be fixed. We were locked out of the account for around 6 weeks, with no refund or compensation for the lack of product provided lost time and effort.
I find if I want anything done, I have to speak to someone through the chat.
Which, to their credit, they are always very helpful, and polite.