It's the little things that make this game unique, and keeps it installed on my hard drive. For a comprehensive look at the game, read strstrep's excellent, detailed review.
I just wanted to add a few things that make this game fun, for me. You really feel in control of the fate of a little, randomly generated Caribbean island. The island becomes subdivided into neighborhoods as it grows, and you can rename these divisions. Have a lot of shanty houses in an area? Call it "Shantytown" or try to improve it by building better housing and creating places of employment around it.
The art in this game has a lot of personality, and still holds up decent today. Not fantastic, but decent. The animations are good, and it's fun to zoom in on your people from time to time and see them going for a stroll or going to church.
You can name each and every individual person on your island if you desire. It's neat to look at your island 70 years from when you started and see the descendants of one of your first residents.
As a city builder, it's a solid game on its own. You need a working economy. Farming usually forms the base of this, but you can also raise cattle, fish, mine, or harvest timber. From there you move to industry, canning coffee and papaya, or making jewelry from gold. You need a high school to educate your people for many industry jobs, and a college to get people prepared to work at power plants.
Where you build is also important. Your people prefer to live close to their jobs, and it'd be nice if entertainment was available within walking distance as well as access to medical care.
Tourism can be a big money maker as well. Creating hotels and allowing tourists to spend money at your bars and restaurants. Or you can create a secluded resort with a day spa and marina.
Each individual citizen in Tropico needs food, housing, religion, political freedom, security, and entertainment. But the neat thing is that each person assigns a different value to these needs. Some people have a greater desire for soccer matches than going to the bar. Others are more concerned with religion than political freedom.
These desires tie into the political game. There are several factions, from communist to religious to environmentalist, and they all want Tropico to cater to their often opposing needs. Increase political freedom and satisfy the intellectuals by building a radio station and allowing free speech to be broadcast. Or indoctrinate your youth by having the schools slanting education in favor of the military. You can allow free elections, allow elections but stuff the ballot box in your favor, or simply declare that there will be no elections (although beware of rebel uprisings).
Edicts allow you to control the island in interesting ways. Double your food consumption and increase happiness. Ban contraceptives and increase the birth rate. Tourism campaigns, martial law, arresting troublesome protestors, assassinating political leaders, setting up social security, anti-litter ordinances, funneling money into your own swiss bank account. Almost all of the many edicts are interesting and fun.
It may seem hard to believe, but this review has really only scratched the surface of the options and detail in this game. I don't want to hype this game up as the greatest thing ever made, but it is unique, charming, and a lot of fun.
The music is relaxing and is suitably Caribbean. Your people move from their home to church to work. When you click on one you are greeted with an accented "Presidente?" or "Hola." You are then brought to a screen where you can see their current thoughts, their family, and their needs and how well those needs are being met.
An in-game almanac allows you to see your entire population sorted by nationality, job, income, happiness, or political ideology.
Your workers places bags of coffee at their farm or crates of goods at the factory, and your teamsters haul wheelbarrows of goods to the dock, which are loaded onto ships by your dockworkers.
Rebels appear in your banana plantations, and military officers decide to join coups. The gunfire is a suitable audio clue that all is not right on your tropical paradise. If someone gets gunned down, their family remembers, and their opinion of you can drop.
It's these little things that make Tropico a great game.