One of my favorite expanisions for several reasons:
Usefullness- unlike Mare Nostrum or Conquest of Paradise which are region specific or padded with features people rarely use, Mandate of Heaven provides features that are helpful to all nations. Edicts are great since you can pay gold for great trade, manpower or religion bonuses in your states. Ages are a nice side feature and gives you objectives as a nation.

For those who like to play in Europe (Central Europe especially) this is a must have DLC, which really fleshes out the region. Plus there is an achievement to colonize australia as austria. I think I do not have to say anything else.

This dlc's content is rather poor in my opinion and I find myself using its few features really rarely. Buy this only if you want a full collection, it wont affect your gameplay experience as a good dlc should.

Nice new features, however the full price is bit too much for me.
I recommend it only on sale.