Four Seasons is a great campaign. The four scenarios are as different as the seasons themself. I downloaded it yesterday and I really had to finish it today. There is one little bug in the third scenario: Since your population limit is 50 you cannot build 25 Heavy Cavalry, 25 Comp. Archers AND 5 Stone Throwers at the same time. Maybe this is why I couldn't win the scenario except by skipping it using cheats. Besides this tiny flaw, the campaign offers a lot of fun with very good design considering the age of this release.
I had some problems with one or the other mission (espacially I failed on the second one) but replaying it showed me that it is indeed possible to win. I would gladly say "5 points" if I could only find a way to fight off a post-iron Choson in the last scenario. Of course, while you are fighting with another post-iron Yamato. Even if you ally with the other two clans I found this simply impossible to break through dozens of towers, legions and priests. The enemy seems to have enough ressources to rebuild all of them as soon as you wipe them out. Yamato don't have catapults or war elephants, so I think it might be simply impossible.
Very high creativity all over the campaign. First of all, you never have to fulfill the same duty twice in these four scenarios. In the last scenario you are even asked for tribute and can thus ally yourself with toher clans. Yet there are no puzzles or something to really make you think. Still, excellent work!
Map Design: 4.5
The maps are very nice with lots of eye candy, for example snow in the winter scenario. You will immediately recognize the season you're currently in if you see some piece of the map. While there is snow in winter, there are brown, red and yellow leaves in autumn and a lot of green and berries in spring while summer will show up with palm trees and some desert areas. Great idea! Of course, the map doesn't look as nice as newer ones but there's only one thing which I really miss: grass patches. There is nearly no use of them.
You are told a little military story about your clan gaining rulership over Japan. Not bad. There are bitmaps and usefull hints. All in all it's a decent work here.