I may be one of the few who likes the Winter Set. I found the optimal layout for it on the Wiki about the event, and I think it was posted there from the beta forums here. Anyways, it's a lot of pieces, but I like it's output. 7 FPs a day, 20 refined goods, attack and defense bonus. It's pretty nice. I also started playing a little bit before the event started, so it was incredibly useful for my city right away. That could be part of my bias, but I still use it because I like it.
I found the combo set configuration for the Cherry Blossom set on the wiki page as well (2x Cherry Blossom set except for 1 Nish pond, plus 2 SoKs). All lvl 2, and I find that set to be awesome. Maybe if the devs decided to release the lvl 2 upgrades for the Winter Set, people would want to use it? I know I would love that.
Still, the new buildings being released for events, including historical ones, are all really good. They've helped me advance my city, as well as my goods output, FPs per day, attack/defense, etc a ton. They really are great for newer players at least.