If you're in an area newly cabled by VM, it will be proper FTTP, not the manky old coax network, so tends to be more reliable. In terms of speeds across the day, those problems are caused by VM's failures to stop selling before local capacity limits are reached, BUT they are unlikely to arise in a new network area, because it takes time for the problem to build up, and because newer areas should have more capacity built in anyway.
Whilst you've evidently had a poor speed experience before, and some people continue to have exactly the same problem, with the same poor responses by VM, I'm highly confident that won't affect a new connection on a new area of network. Other than that, the service is normally stable, solid and consistently fast. Customer service however, appears now to be even worse than a few years back - the same crap offshore support by slaves who don't understand anything and don't care, now supplemented with even crapper "chatbot" responses on the phone intended to disconnect customers before they can even get to the offshore numpties. A very few connection problems go round and round with customers tearing their hair out in frustration at VM's staff insisting there's no fault when there very clearly is - peruse some of the longer running threads in the speed and gaming sections of this forum, although again on a newer fibre optic area things should work more reliably.
The other thing to watch for is VM have been having months and months of severe problems actually connecting customers, because the company's pre-installation processes have simply collapsed, and you could find that you are connected quickly and efficiently, equally you may face months of broken promises, missed appointments, and the misery of repeatedly dealing with VM's Kafkaesque customer contact. Again, a look at longer running threads in the Quickstart, Setup and Connections forum will give you an idea.
On balance would I recommend VM? Yes, but caveated that you should not terminate the BT connection until VM is actually installed and running, and has proven fault free and as promised for a couple of weeks. That also means you can cancel the VM connection if there's problems under cooling off rights, without messing around your existing ISP, although if you stick with VM you might have to jump through a few bureaucratic hoops to get the BT landline number transferred once the VM contract is running. You also need to accept that the only credibly effective place to get in touch with VM, or get support is usually this forum, where the great UK based staff (assisted by the amateurs) will do their best to resolve any issues without the misery of having to deal with VM by telephone. Even if you get the latest Hub 4, the wifi is poor, particularly compared to BT hubs, so at least be prepared to budget for buying your own mesh wifi system (say £100); VM email seems to be erratic, with patchy spam filtering, and a history of authentication and access problems. I can't comment on VM's TV services. Consider your speed requirements carefully - you can probably get a 1 Gbps deal, but do you need that? You only get the new customer discount once, so "in contract" upgrades are usually poor value, and the best value will be judging your speed needs accurately and selecting the right speed up front, unless the speed is defined entirely by a TV and broadband package you choose.
