Final feedback on the event from my perspective:
1) Special Event buildings were mediocre at best. Definitely good for lower Age players, as it would help them with Population issues, but the size and bonus' given were only so-so for the footprint the Bakeries would take up
2) Prize structure to build the Special Event buildings was fair, 2 full Bakeries and one upgrade (or two depending on luck with incidents) short of a 3rd Bakery.
3) Daily Prizes were relatively good. Most I would not use, but I was able to get the balance of Kits needed for Winter Spire (still not sure if I will build it), as well as a fully upgraded Train. Was all dependent on chance of course, but a player who saved their Stars for particular Daily's would have a reasonably good chance of getting what they needed.
4) Reindeer Sleigh - I think most players would disagree with me, but a rare option for Pay-to-Play players (or those disturbing diamond farmers) to get a little something extra. Nothing out of this world was offered, but it was reasonable. Why should everything go to Free-to-Play players. Would not want to see this happen too often, but at Christmas time, a little extra bonus for Pay2Play seems fair.
5) Advent Calendar - really did not like it at all. First off, nearly all the prizes were of very low value and the only real reason to play it would be for the Calendar Collection Reward. On a scale of balance, it was not worth participating in, except for the odd Calendar Key, or getting lockpicks if the Daily Prize offering was also of very low value. I basically saved my lockpicks until the end, and then took the 3 FP offerings and a couple other items that were of some value to me.
6) The length of the Event was a little longer than I liked, but I think that would basically because there was no real desire to achieve anything in the Event, other than getting a Charcoal Train for the Attack Bonus. Once I had it, there was little left to do - Reindeer Sleigh-strike out, Advent Calendar-basically strike out, Daily Prize-once I had the Charcoal, only item of any kind of interest was 1Up kit as I plan to Age up in the next day or two.
If I had an over-all rating, probably just a 6/10. If the Winter Train Kits had not been offered as a Daily Prize, than 4/10.
I have looked towards the Beta for the 2021 Forge Event, and unfortunately, it appears also to not have much to offer, beyond some of the Daily Prizes which can be quite decent. The Special Event building, like the Winter Event, (as it currently appears) is also quite mediocre and I will most likely sell it - but as with the Winter Event, at least the Population bonus will be good for the lower Age players.