There's no doubt that Virgin Media supply the highest widely available speeds in the UK (and probably Ireland). I have the M200 package and have consistently high speeds of 220-222mbps. Upload about 21mbps.
Unfortunately also there is little doubt they have the worst (apart from probably TalkTalk) customer service of any any ISP. The Off-shore Call Centres are so bad they deserve minus stars alone.
My suggested VM Golden Rules:
1 If buying a package, only sign up to vouchers/cashback via a third party website, never anything verbally from VM.
2 Brace yourself for the "hidden" £35 Activation Fee which appears when you have completed your order even if you have opted for "free installation".
3 Transferring an existing landline number from the Openreach network to VM is very hit and miss, even if you have opted for this when signing up. Contacting VM again after a week is recommended as it is often not actioned at all.
4 If a Hub 3 is supplied, use it as a modem only and buy a decent router, and have full control of your broadband.
5 Rectify any problems via the VM Community Forum, as the off-shore call centres are a waste of time and effort.
5 Call the Retentions Team when you contract has ended and the monthly payment has risen and negotiate a new price, this might take a few calls to get a decent discount.