Last night, four of us played Carcassonne using the Wheel of Fortune, fan-based Seasons and fan-based Family Fued. So here is my review for the Seasons Expansion:
12 tiles is definitely a good number. The only complaint that I have is that 47 season conditions is probably a bit of an overkill, when you're only using four in a random order. I think 14 would have been sufficient.
At any rate, it did seem to add a little strategy as well as a little luck to the game. For spring we had cloisters +2, summer was roads -2, fall was roads +2, and winter was cloisters +4. I seemed to only be able to complete a road when the roads costed 2 less, no one else seemed to have that problem, but that's where the luck came into play or lack of luck on my part.
Overall, I enjoyed it. It seemed to work well. Although, I may need to find better friends though as they never paid attention to the symbols on their tile for when to advance to the next season.