Well, I finished my Welsh campaign. I have to say, the whole culture system started to piss me off. It takes far too long to be able to retrain your armies once you take a city, which bothers me because I like to take more or less full-strength units around. Also, by the end, my units had really begun to flag in terms of quality relative to the Scottish and Norwegian units. Since so much of the fighting was done in cities, my lack of heavy infantry became a big issue.
Right, so, the Scots let me fight the Norwegians for a little while, but eventually turned on me. Before, I had a decent invasion plan to cope with the fact that I had to go around Scotland: I landed troops on the islands to the west of Britain, as well as in the northeastern corner at Wick (a barely garrisoned citadel) and one army that actually marched through Scotland. This worked out pretty well, as I was able to attack them from all sides. The Scottish betrayal was a bit of an annoyance, but nothing I couldn't handle. After all, I had about 20 provinces by then, so I just outproduced them, even though my armies kinda sucked.
By the end, I conquered all of the isle of Britain except for Aberdeen, Scotland's only remaining city. I also had most of the little surrounding islands. I ended up killing the entire Norwegian nobility and knocking them out, although I didn't have all their settlements. I had to take Dublin to win, since it's a requirement. Ireland had retaken their isle and seemed content to just sit there, loyal allies that they were. Odd thing about taking Dublin was, the Irish had had giant swarms of armies sitting in the countryside around the city practically the whole game... until I started transporting troops over. Then they kind of evacuated, and the fight to take the city proved pretty easy. I don't know why they did that.
Now I'm in the Americas. I tried being the Apachean Tribes, since they get horses and guns eventually, but they kind of sucked. The settlements around their initial province are really far apart, I didn't understand their system of buildings (something with tents... I dunno), and there wasn't much strategy involved in conquering all the little rebel settlements. I just kinda swarmed in. I would have dealt with it anyway, figuring that it would get cooler once I got horses and guns, but one of my three armies randomly deserted, and I didn't feel like dealing with that.
So I just went with New Spain. I have to say, I don't feel all that challenged, but it's still a lot of fun. There's a fair amount of strategy in conserving your tiny forces while still actually winning battles over and over. And you have to win plenty of battles... the Aztecs and Maya have huge armies, and lots of them. The cannons, guns, and horses make it possible, as do the huge treasury you start with and the native mercenaries you can hire as expendable infantry.
Spoiler Below And things really start to get interesting once other Europeans enter the picture.
...anyway, I've always liked fighting continuous waves of huge armies. That's why the Alexander expansion to Rome was probably my favorite installment in the series. Being New Spain provides something of a similar experience, although I think Alexander involved a greater imbalance (and was therefore still better). Currently I've got 24 out of the 30 provinces necessary, and I've beaten the Aztecs back to only five cities. Bastards actually took Vera Cruz, and I got a promotion while they still had it, so it's worse than it would otherwise have been. Oh well.