There is something about Cuba, the romance of the Revolution and it's charismatic leaders Fidel and Che, the faded colonial architecture and the peoples staunch stance in the face of US aggression, that make it an appealing destination.
Steeping onto the streets of old Havana is like stepping through a time-warp, the faded colonial architecture and beat-up 50's Chevrolets weave an unusual spell, creating a truly charming atmosphere that sucks you in and refuses to let you go.
The people of Cuba are it's greatest treasure, they have come through a lot surviving oppression (under Batista), revolution and grinding poverty (thanks to an illegal blockade) but have come through with a smile and a refreshing lust for life that is infectious, get to know them.
Quick Tips:
Avoid anything that is state-run, the state-run restaurants and hotels are uniformly appalling, far better are the Paladares, private restaurants run from peoples living rooms, and the Casa Particulares, spare rooms rented out by house owners are vastly superior and give an insight into Cuban life.
As a foreigner you will be expected to pay for everything in dollars, but it can be useful to carry a small stash of Pesos and to seek out some of the out of the way places that will except it, not only are they significantly cheaper but they are also a lot more friendly.
The Cubans are one of the friendliest people in the world, and even if you don't share a word of the same language, they will spend hours just chatting away to you. There are a few unsavory characters that will befriend you purely for your dollars don't let that poison you to the genuine people.
Best Way To Get Around:
The highlights of Havana are within easy walking distance of each other and indeed much of the old town is pedestrianized, the streets are safe thanks to a large and visible police presence so there is no reason not to enjoy the city on foot.
For travel further afield the authority's have a network of trains and buses especially set-aside for tourists and dollar paying locals but these can be very unreliable due to the shortage of petrol thanks to the US blockade. The local Peso trains and buses but it's practically impossible for tourists to get on them.
Finally there is Cubana, the Cuba national airline which has a network of local flights to all the major destinations, but the fleet of aging Russian prop-planes are rapidly falling into disrepair which may account for it having the highest ratio of death per passengers, but it's a cheap white-knuckle ride if you're up to it.