I recently visited Cuba & was quite disappointed, firstly you have to have booked flights & at least 1 nights accommodation before you can apply for an online visa which costs you around £30 per person. In Cuba there are 2 currencies – the national peso used by the locals & the Cuban Convertible Peso (CUC) used by visitors which can only be bought & used in Cuba & worth about 24x the National Peso. Do not take American Dollars as they are subject to an extra 10% surcharge on top of the exchange rate. Take cash as many places especially outside Havana do not take credit/debit cards, especially American backed ones. You can exchange cash at the airport,the banks & the hotels but you need to take your passport along. Only convert as much as you need as you will have to convert any CUC (notes only) back to sterling before you leave.
A lot of Old Havana is in a poor state of repair, whilst the best preserved areas tend to be tourist traps with very high prices for food & drink & the locals trying to take advantage of tourists. In their defence Cubans really struggle because of the American embargo, which along with the Communist control has resulted in a very poor economy – in the rural areas many people travel in pony & traps & farmers use oxen to plough the fields.
One of the highlights, as a byproduct of the embargo is the large numbers of American classic cars – such as Thunderbirds, Plymouths & Cadillacs, some in immaculate condition.