[danatkinson]

I agree that living conditions will undoubtedly be hard at first, but will only improve from there.

The first humans to live on Mars will almost certainly already have gone through many months/years of rigorous on-Earth testing to ensure they don't go stir crazy. Indeed, MARS-500 is a wonderful, recent example of research into this area.

By the time 'ordinary' humans get to Mars, there should be a reasonable amount of infrastructure (power/water/heat) already in place to support a population.

As for entertainment, I don't imagine that football stadiums or theatres will be required in the future if everyone had access to something like an Oculus Rift.

[seren]

Nothing is unmanageable, and it is obvious that an engineered habitat will be less "diverse" than Earth that have evolved for billions of years. Take food for example. The basics will be available anywhere in the Solar system, but you are not going to eat fresh seafood or truffle. I know that this sounds pretty trivial, but lots of what we are taking for granted on Earth will need lots of careful planning and execution to get elsewhere.