Go read the forums on Steam - linked here for ease: http://forums.steampowered.com/forums/forumdisplay.php?f=742
The original devs are all gone, they're basically adding a few new structures and calling it a new release, it still has some game-breaking bugs that have persisted for 3 or 4 releases now.
I highly recommend Tropico 4 - you end up with more control over individual structures than you did with the Sim City series, but it is equally fun.
Steam even has the Collector's Bundle (Game + Expansion + all the DLCs) on sale for $9.99 through March 15, 2013. http://store.steampowered.com/sub/19282/
Sadly, Tropico 4 has an online-required component - you have to create an account and sign in to launch it each time. About the only issue I have with it, otherwise it is awesome. (I haven't tried it offline, my laptop won't run it well so I play other games when traveling)