It really is pretty amazing (although yes, the second part is relatively meh). I wouldn't compare it to something like F/SN because F/SN is a huge narrative masterwork that you need to slowly digest and appreciate, whereas I consider PW to be more of what I call a "popcorn" game: entertaining without being too deep or thought-provoking (a category some of my guilty-pleasure nukige fit into as well). PW has some of the best production values I've seen so far, to the point where I was kind of spoiled for moving on to other games, particularly older ones. The art is way above par, especially the paperdolls (which have way more detail and variety than a lot of other games), the music is excellent, and it manages to convey a surprising sense of movement and action during the battle scenes for a game with only static images. Plus the card battle system is quite good for a minigame; gives a good break from the reading and makes you feel a little more invested in the action (unlike a certain recent mangagamer title I could name...). Probably the biggest weak point is the plot, which is passable but not excellent. The characters are likeable enough, but with a few exceptions they aren't really all that interesting, and none of them is terribly well-developed.
tl;dr: it's a good game and you should really play it if you haven't, especially because it's not particularly long.
(edited to remove poorly formatted quote)