I've been playing the civilization games since CivII and I've played Freeciv and I wouldn't really agree that it's more complicated than CivIV. Firaxis delt with city spam strategies by reworking corruption and introducing happiness. Freeciv is a straight out CivII clone and the only thing keeping you from covering every land square in the game with cities is the artificial limit they put on city density (which is adjustable) and the fact you can't build on tundra squares (might be adjustable as well, I always played with it disabled).
I'm not saying the game is bad, it's good (and so is CivII), but there are a lot of things from the later games I think are lacking (strategic resources and luxuries, culture takeovers and border expansion based on culture rather than zone of control, religions, being able to build cities in space/under the sea/floating in air/in hell). I'm not entirely familiar with the goals of the developers, if they are just trying to do a straight up clone of CivII or if they want to get the core game done before they start adding things, but I certainly hope they're open to adding new or reworking old features.
One thing I really like about Freeciv is how customizable each game is. As I recall there are hundreds of options and riles you can tweak.
