A few hints and tips for those playing the demo.
Grouping ships or units is very useful in Empire, and groups work different in naval and land battles.
Naval battles - at sea when you group units they will try to maintain relative positions an also follow the lead ship around. So if you group your ships in a line they will then move in a line around the map enabling you to more easily control large number of ships. Also using alt + giving attack orders will have your ships in a group prioritise firing on the target ship and not break out of the group formation like a normal attack order.
Land battles - when you group units the group remembers the relative position of each unit so when you give a move order to a group they will end up in the same relative positions as when you grouped them. This, in combination with the new rotate/move buttons on the HUD allow you to quickly and easily move groups around, and even to break off parts of a formation into a new group.
You can time when your infantry fires in land battles. Simply turn fire at will off, units will reload even with it off as long as enemies are not too close, and then click fire at will back on and your unit will fire at any enemies in front of them.
I've seen several people asking what happened to double right click zoom-to camera functionality, this has now moved to double mouse wheel click.
I hope these tips help with your enjoyment of the demo.