We completed the third mission for TIME Stories this weekend (A Prophesy of Dragons), and it was very enjoyable. We'd started it a couple weeks' prior, had to break (after a 3 to 4 hours session) and came back to it for another couple hours. No spoilers here, so read freely.
The consensus in our group of four is that Prophesy was better than Marcy Case, but not quite as good as the mission that comes with the base set. The base set mission has more plot-relevant puzzles (which we all enjoy) and generally feels more thought-out in certain ways--they furthered the mystery. The decisions in that first mission also felt more "deep" in a way--it felt like the consequences matched well and made a strong story-sense in terms of the plot. Marcy Case's decisions were similar in this quality, actually, but the overall experience felt thinner and the puzzle/mystery aspect was less satisfying.
Prophesy, meanwhile, was very deep in mystery and in activity--longer than the first two missions to be sure, which was very satisfying, and aside from the mission itself, there are also tangible elements of a long-arc plot that (we assume) stretches across all the mission expansions. This had us talking a lot after the game, which I always take as a mark of a great experience.
Where the mission didn't please us as much was in its lower amount of puzzles and clue-gathering. There was one very challenging puzzle, and aside from that, I don't recall any others. This is not to say that we're playing these for puzzles (we're not), but I think we appreciated the manner in which various puzzles and clue accumulation were integrated well into the plot progression of the first mission, and that has sort of spoiled us for wanting that in each mission.
What Prophesy lacked in puzzles, it made up for in character development, which was much stronger than in the previous two missions. There is a bevy of items that can be collected and used to enhance your character's abilities, and real choices must be made about what to acquire and what to pass up, and then how to arrange your party at each location to balance your abilities. Having 8 characters (or vessels) to choose from at the start of each run is also a major plus, adding to the strategic aspects. I switched at one point as we started a new run, and it made a real (positive) difference.
It's interesting to us as well that, so far, the three missions have all been very distinctive--not just in them being in very different time periods and settings, but in the way you're expected to reach your goal and what you need to really focus on. Just because one manner of playing worked in one mission doesn't mean it will work in the next. The developers have so far done a wonderful job of creating a feeling of very different yet clearly linked games. We've already bought the remaining available expansions and will likely be playing those exclusively on game nights until we run out : )
One last point--people here have asked about playing with less than 4 and whether that will detract from the experience. For this one, I really feel that 4 is very optimal. This can be achieved with 2 players handling 2 characters each if need be, which would work to much less detriment than in the previous missions (IMO). With three players...I think it could be done with three certainly, or perhaps let the most experienced player handle two characters. For this mission, 4 characters seems to me almost necessary to the experience.