As the event winds down, my reaction to the "random" quests and infinite questline is ... meh. I did about as well in this event in terms of prizes as I did in Summer Solstice, a little less well than in the Phoenix event. (8 artifacts for this and Summer Solstice, 9 for Phoenix). I didn't spend nearly as much time playing, interacting and thinking about the game as I did either of the two previous events in which I've participated. It wasn't as much fun for me without being able to plan (I only barely got into the 64 quest line). So even though I got some nifty prizes, I didn't have as much fun doing it, which makes it overall not what I would want in an event.
I think a lot of the prizes are more oriented toward players in higher chapters with the mana and seed production, but that is probably a good thing. In chapter 4 I don't need more event buildings than the ones I got in Summer Solstice. But the buildings are really pretty! I like the creativity.