Good addon but with flaws.
It's hard to review this expansion as 1 big addon because it adds 4 extra separate campaigns so I will review each campaign individually.
First off, the Americas campaign:
The playable factions of the Americas campaign consists of Apachean Tribes • The Aztec Empire • Chichimec Tribes • The Mayans • New Spain • The Tarascans • The Tlaxcalans and the unplayable factions (usable in custom battles, not campaign) are • England • New France.
And now for the fun factor (the most important part,) the Americas campaign is a very fun one (and it takes a lot for me to say that -- normally i'm not a fan of the campaigns of the Total War series; I mostly do custom battles) also as far as new units go there are a lot of unique units among the assorted factions (unlike the base game *cough* the italian factions *cough*) so each faction feels unique.
My rating of the Americas campaign would be an 8 out of 10.
Now the Brittania (British Isles) campaign:
not a lot to say about this one the playable factions are England • Ireland • Norway • Scotland • Wales. the unplayable faction is (again, custom battles only) the Baron's Alliance.
Now the fun factor. Meh, it's an ok campaign but not great and the factions seem like CA just copy/pasted Scotland's (early period) unit roster into most of the factions (- England -- they got their own from the base game).
The rating I would give this campaign is a 6 out of 10. It's a fun campaign but it is easily forgotten and the factions are mostly the same unit-wise.
Now the Teutonic campaign:
The playable factions are Denmark • The Holy Roman Empire • Lithuania • Novgorod • Poland • The Teutonic Order, and the unplayable factions (again they can be used in custom battles) are Mongols • Norway.
The fun factor -- this is a good campaign as the factions are fairly unique (no carbon copies like in the Brittania campaign) as far as units go and the campaign map is a good size (again other then the brittania campaign.)
I would rate this one a 7 out of 10 -- better then the Brittania campaign but not as good as the Americas campaign.
Now the Crusades campaign:
The playable factions are Principality of Antioch • The Byzantine Empire • Egypt • Kingdom of Jerusalem • The Turks, and the unplayable factions (again they are playable in custom battles) are Mongols • Venice.
Fun factor -- this campaign is also good, except the factions are not quite as unique. The Byzantine Empire is basically The Byzantine Empire of the base campaign (other then the Greek firethrower, my favorite unit in the game.) The same is true for Egypt and the Turks. The Principality of Antioch and the Kingdom of Jerusalem are both very unique (mostly all unique units.)
I would rate this one a 7 out of 10. It's better then the Brittania campaign, about equal to the Teutonic campaign but not as good as the Americas campaign.
The overall rating I would give the full expansion is an 8 out of 10. All of the campaigns included are fun to play.