I've been keeping track of my quests after reaching 90th, the last quest segment and have some stats to share from the 214 quests I've done:
With this I've finished the second brown bear, so probably I can call the event a successful one for me. I hadn't used any diamonds, and only bought the event outpost, about which I regret since it doesn't make any difference on this scale. Despite the fact that the event resulted for me in a huge boost for my city, I really dislike it's design.
1) 3 out of for most frequent quests are the ones that may have a permanent effect for your city. I'm in the Elementals and will probably hit the expansion limit before the event ends. If the trend continues illI be massively overscouted in half a year.
2) It has been said many times before, but the quests are very repetitive. My "best" streak is 4 scouts in a row and if not for the time boosters it would be extremely hard to get anything that's really worth it from this event.
3) Workshops and manufactories requirements are a bad idea. I had to make a mess out of my city and went from zero workshops to 11 and soon 16 and from 2 manufactories to 11. Without the warning from beta I would be sitting for a week to even start the event.
4) Very related to the previous one, making us use our normal city production for quests is bad. I hadn't collected from my mermaids or manufactories for several days in case the production quests show up and I can't even imagine how hard this event is for someone who relies on the workshops for supplies.
5) The new requirements make you completely halt your city development. In previous events it was great to advance in chapter mid-event and start getting better prizes. Now I'm sitting at the end of the chapter for a week and will be for 11 more days, because the chapter advancement means days of upgrades to be able to continue.
6) This time your event performance is very dependent on your stocks of time boosters, goods, free space and population. Not to mention the willingness to destroy your city. Even at the previous endless event it was possible to do much without the proper starting conditions, but here I can't see one performing well without a lot of everything to begin with.
Overall the event doesn't make me hate this game, but I would definitely prefer to have fun during the actual event and not only when thinking that all this struggle would be beneficial for me in the future. I really hope that all these issues would be addressed before we start losing players because the event are as painful as the old FAs.