My mum's been with them for years and has no issues with them. She's on a legacy 3G package though and refuses to change simply because the VM support over the years reduced the monthly cost to something really low. They use the EE network so if you get good coverage with them in your area, you'll be fine with Virgin.
They keep trying to get me to change to a 4G package but I've told them unless they can price it the same I'm not interested. Useful having free calls to other VM mobiles and land lines to as loads of people round here have them.I almost went VM when they had a previous decent deal on when the 100 GB one was running but I noticed at the last minute they don't allow tethering so I went with a new option called Smarty which is actually another brand of Three's. Not quite as cheap as the VM offers but no issue with tethering and you get a discount off each subsequent month for the data you didn't use in the previous month.
they don't allow tethering