I was a kid back in England when VAT was introduced. 12.5% if I recall correctly. It was supposed to inflation-neutral, because many "essentials" were exempt. It wasn't, it was massively inflationary, and how could it not be. It added 12.5% to the cost of almost everything.
Also, my father ran his own small business, and (as has been mentioned above in this thread) got jammed in the middle. He became his own tax collection agency, responsible for filing VAT he collected from his customers, and responsible for clawing back VAT he paid to his suppliers. Everything was always out of sync, causing him to have to carry a line of credit just to deal with VAT issues (then they jammed interest rates through the roof to control inflation, but that's another rant).
VAT is insidious as, over time, it gets forgotten as it's hidden in the price you pay. It's not charged separately at the register, it's built in from the factory to the consumer. That way, once you get used to paying it, they can tweak it up a notch from time to time. Then you find out, like the UK did when VAT had already crept to 17.5%, that they plan to bump it to 21.5%. That happened a little while back, and the govt. in power at the time got its hat handed to them in the next general election.
I fully understand that revenue needs to be generated by the government and that, as a relatively well-off dude, I have to pay my share and perhaps then some, but VAT is not the way to go. It's underhanded and designed to fool people into being unaware of just how much tax they are paying.
One last comment for travellers to the UK. If you buy anything of notable value - get a VAT receipt!! You too are paying the hidden tax, but if you are taking the goods out of the country, you can collect it all back! Nice, eh? Just take your VAT receipts to the Customs and Excise window at the airport, and they will give you cash (in sterling) or credit your credit card. The VAT return is the equivalent of a 15% discount. It adds up!