VM when it works properly is a pretty good service, no DSL related issues to deal with, so no fragile lines, no distance related issues. No DLM issues. But do get occasional transit/peering issues still.
So sadly VM it really depends where you live, I think some areas like Leicester the original network that was built is very bad, and it needs a complete rehaul to be upgrade friendly which I assume is too expensive for VM to take on so the upgrades carried out are insufficient every time, whilst areas like ignition's are to get a upgrade friendly network layout so they may not have capacity issues.
Then you also get the areas where I suspect subscription levels are too low, which is good for contention but not so good for profit, which also means the area's with high take-up are under pressure to have over selling to make up for the under subscription areas.