Pros:

Large non-linear maps
Clever level design
Detailed and variable areas
Loads of blind aleys adding to the sense of 
Mood shifting with each new area
Great feel for the various faces of Japan (from tight urban spaces to rural and mountain areas)

Cons:

Some minor bugs (got stuck for a while in one location, but only once)

Conclusion:

A relaxing campaign with amazing level design, epic maps and a great eye for Japan (without the usual in your face quote-spotting typical for fan depictions of Japan). Not the hardest campaign to play but definitely one of the best in terms of originality and variety of areas. Great fun.