When we found out that US embargo on Cuba will be lifted, we hurried to visit it before it changed too much.
Cuba is an amazing mix of Caribbean vibe, 1950s Cars, French architecture, and socialism, not found anywhere else on the planet.
During the trip we haven't had an Internet access for a single time, which was part of the experience. This is definitely going to change. Having a Lonely Planet book was very handy.
The country has 2 currencies: peso nacional and peso convertible. The latter is pegged to US dollar and what you get when exchanging the money in the bank. Forget about card payments and ATMs. Bring cash, and it better be Euro or GBP or CAD, because at the time of writing there was a 10% surcharge for exchanging USD. All tourist services are priced in the convertible, as well as some goods are can only we bought for them, like baby diapers and long-shelf milk (yuck). I recommend to get the local peso, e.g. by exchanging on the market, then can also visit restaurants and cafes for the locals, which can be 10 times cheaper.
Apart for a few cocktail scams in Havana, the country feels pretty safe - do not say to anyone on the street that you have just arrived or you will be invited for expensive ~$5 cocktails, paying for the host as well. The regular cocktail price for tourists is $2-$3, and you can make yours for even cheaper - rum is readily available in most shops, even if they don't sell much else.
Do not book any hotels (maybe only for the first night). Much better option is Casa Particular - Cuban home stays, allowed some years ago by Raul's reforms. They cost $15-$30 per night and you get to see how local people live and the accommodation will be better than in most hotels. They are easy to find, because they bear an official logo, or you can just ask on the street. They will be also happy to cook a dinner or breakfast for you for an additional charge.
We took a southern circuit to Santiago de Cuba, by train/buses and taxis. Inter-city taxis can sometimes cost the same as bus, with the opportunity of riding old, but good looking 1950s American cars.
Food in Cuba is generally not very good, probably due to a long isolation. Mostly you get meat with rice and beans. The exception is Baracoa in the South-East, where you get coconut-octopus-curry or pork-in-chocolate-sause, etc. Highly recommended!
Bay of Pigs is incredible for diving - no PADI licenses, but cheap and good service. You will see wrecks of American ships from the 1961 failed invasion lying on the edge of 300m deep underwater cliffs and lots of Caribbean marine life.
I don't recommend renting a car because you won't get a 1950s one for a self-drive. It is better to move by public transport and occasionally rent taxis to go anywhere you want with a style. There are lots of lots of these old cars to enjoy!
People are very communicative and helpful, but basic understanding of Spanish is necessary. Some older people may even speak Russian, but almost no one speaks English (with the exception of touts in Havana). While being relatively poor, people remain happy, and socialist system ensures that everyone receives education and medical services. You won't see anyone homeless.
Cuba is home to many things in popular culture: enjoy Mojito, Piña Colada, cigars, Salsa, and the revolutionary spirit of Che!