A good game, but lacking the magic of the original.
Right, I've played this for quite some time now so I thought I'd be the first to write a review based on the actual content of the game.
Firstly this expansion pack should be commended in terms of value for money, you actually get 4 different campaigns, each with its own desktop shortcut thus making it feel like 4 expansion packs, although this comes at the cost of installing each campaign seperately which takes a while.
Britania campaign:
This was the first campaign I played. You start off in in the early medieval period with the objective of gaining dominance over the British isles, or, if you play as the English faction who are already dominant your aim is to push back the Scots and claim Wales.
For the first time we see an introduction of actual Welsh and Irish factions rather than the'rebel' groups from the main game. This seems like an exciting feature, however it is severly let down by the developers' downright lazyness. For example, the Welsh have the same accent as the English and the Irish accent is the same as the Scots. It would have taken little effort to record a few new voice-overs.
We see a similar story with the 'new' units, for example, playing as the Irish or Welsh we just see longbowmen that look slightly different, or Hobilars renamed to 'hobiguires' with a slight change to stats. This again is a dissapointment.
On a more positive note, they have done a very good job of remodeling the campaign map which shows Britain and N.Ireland from a closer perspective with the mountains in more realistic places and a good variety of smaller settlements like Gloucester that weren't featured before. You also get a larger selection of generals which is useful for maintaining social order, particularly as rioting has become far more common.
To conclude, this campaign could have been amazing but the potentially epic battles are marred by the Welsh taunting you with posh English accents. I was quite dissapointed with this as I had always seen the makers of the Total war game as perfectionists who actually care about the presentation of their games. Hopefully they'll bring out a patch with the correct accents.
Americas campaign
I played this campaign next. You have a choice of several local factions such as native American Indians and two Aztec groups. The are the easiest to gain substantial amounts of territory in the early stages of the game, however as the newer factions appear you will find yourself being destroyed in battle by the well armoured spanish conquistadors and their English and French counterparts. Thankfully you can also play as new Spain which means battles will be easily won in comparison.
Overall this campaign feels far more polished than the Britania campaign. The Native American faction features a vast array of new units such as medicine men and scouts, plus you can get troups with captured muskets etc later on in the game.
Teutonic campaign:
I have played this the least. The first thing I noticed is that they haven't bothered to re-do the territory map. By this I mean the one done in various colours for each territory in the bottom left of the screen. Instead they've just zoomed in so the picture is grainy and pixelated. Other than this the campaign is quite fun. It's probably the most similar to the main game as you get all your traditional medieval units. I haven't played this enough to really comment but from what I've seen so far is quite promising.
The Crusades campaign
I've started this lately and really enjoyed it. I'm playing as the Jerusalem faction which is basically the remnants of the English crusaders sent to take the region. You get historical generals like Richard The Lionheart and King Baldwin of Jerusalem. This gives a good realism to the game and helps emerse the player in the action. Richard The Lionheart for example, has a 'lions call' special ability where he rides around the battlefield rallying his routing troups, causing them to run back into battle with increased morale. King Baldwin, your initial faction leader also has insanely high stats and is already a top class general at age 18.
I found this the most epic of the four new campaigns and I'm currently enjoying giving the Turks a good thrashing and trying to fend off the Mongols.
Overall
A good expansion to an amazing game. This could have been better but I think they must have struggled with time towards the end of developement. Hopefully they'll bring out some patches to improve on the voice acting etc and then this game will be able to shine.