ORIGINAL: Dragoon
I find the tooltips explain most things, although it's missing detailed background information about mechanics, which leads to confusion how things actual work.
Like pollution. Maybe in an extended tooltip it should not only show the source but also explain the process how it's created. Instead of me shifting workers around to get actual numbers how much pollution each different production unit creates.
Mouse over the pollution icon in the upper left hand side of the city screen (in the Statistics box) and you will see the breakdown by worker type. [:)]