The product is great. I pay for 100Mbps broadband. Every speed test I've done is 102-110Mbps. With BT Fibre, I was getting 18-25Mbps.
The business itself is totally useless. I signed up a month ago. I've still not seen a copy of the contract. I've now requested this five times. Same goes for my account number, which they cannot give out over the phone. I haven't seen my bill as a result; I had to get them to read it out to me. I should be paying £25/month. My first Direct Debit was for several times that. It turns out that was in part because the first payment is for two months, in part because they were over charging me, and in part because they charged me for installation and activation, despite it saying both were free on my pre-contract. Oh, and they failed to switch my phone line over from BT.
I asked to cancel on the basis of mis-selling, as they were refusing to honour what was written on the pre-contract. I was told it's not possible to cancel as I'm outside the 14 day cooling off period, as written in my contract. I told them that they have no grounds to hold me to the contract as a) they were refusing to honour the terms of the agreement, and b) they had failed to supply me with a copy of my contract, or access to my bills and account. It literally says on the Pre-Contract that the terms are, in this situation, unenforceable without a court order (which they wouldn't likely get). The response was along the lines of "You can't just delete our emails and then pretend you haven't seen them. You've agreed to a twelve month contract and cannot expect to leave penalty-free."

Yup, apparently I planned this weeks in advance, and wasted hours of my time chasing them for access to my account and a copy of my contract, just so I could pretend I haven't seen them, all as preperation for them screwing up.
In the end, after almost half an hour of arguing with him, he spoke to his manager. My tariff was changed to the correct one, an account credit was given to make up for the over-payment, the switch over from BT was actioned correctly, and he'd offered to manually send my account details through to a second email address (I asked for a paper copy, but apparently this is only possible with paper billing at £1.75/month. Once activated, it cannot be deactivated). I'm happy with that, assuming it's all correct. Another operator confirmed the changes when I phoned back half an hour later, so I'm reasonably confident I'll at least be charged correctly now.
Still no email though
They're useless TBH. If we could get high speed fibre over a BT line, we'd avoid Virgin like the plague. But 18-25Mbps for Fibre prices simply isn't good value for money. I only switched away from Virgin last year as BT were practically giving their broadband away in a new customer cashback offer, and Virgin wanted silly money if I stayed with them.
TL;DR: Great speed. Really reliable. Useless customer service.