Tropico 3 was one of my Steam sale purchases and I'm thoroughly pleased.  In recent years, you'll be hard pressed to find as good a city simulator game.  Nor does this approach the (almost needless) complexity of Simcity 4.  It strikes a good balance between entertaining and difficult.  The campaign is an island hopping game where each island presents a different goal to accomplish with different elements working against you.  For example, my current game I'm on an oil rich island which is attracting tons of immigrant workers.  This is pissing off my Nationalists and causing them to go rebel.  It's also pissing off the Commies because I can't provide housing fast enough.  Therefore, people are turning rebel which in turn pisses off my military faction.
All in all, the game is a gigantic balancing act of figuring out who's needs you need to satisfy first.  The early missions (the demo) are relatively easy because the elements working against you aren't so time critical and once you setup a decent economy it's smooth sailing until you meet the scenario's goal.
If you played the demo and was bored then yeah, don't get it or wait until it drops lower in price 6-12 months from now.  But if you like city simulation games then I don't see how this could be considered boring.