accelerated production means that everything takes half as many shields to compleate. eg a worker becomes 5 shields etc. this cuts all building times in half and so speeds up the game. this changes the build order i like to implement.this also changes the shields-food ratio needed for settler and worker creation which changes citizen managment and starting stratergies. one nice thing i like to do with those useless totally corrupt cities is to make worker factories which can now spit out a worker every 5 turns.
Everything costs half, including research. But unit support still costs the same.
In my opinion the most noticable difference is the importance of forest. The 10 shields that cutting it down produces all of a sudden make a huge difference on the build. For example: a seafaring civ can create a harbor in a remote (therefore completely corrupt) city in just 5 turns just by cutting down a forest.
The other difference is (if I remember well) that worker actions still take the same time. So you need more workers to keep up with infrastructure in relation to your population.