The first encounter is basically just filler--although in the game I ran, the players could have sure used it to shake the dust off as it had been nearly four months since the previous adventure! It only serves to tip the players off that there may be other people in the area, possibly with their own agendas. Which is an interesting setting detail, but does not further the story at all, and neither does the follow-up encounter it sets up. It's just for filling up run time.
The keystone combat encounter proved to be very challenging to my party--including one (albeit temporary) fatality and lots of yo-yo-ing by the tank. I really liked the way the monsters in that fight interacted, and it was definitely the high point of the adventure. The theme in this combat was really good as well, and served to reinforce the connection to the source material this trilogy is referencing.
Then all that theme gets cashed in when the party solved the final puzzle, only to get the stupid password that makes no sense as an in-setting reference, but rather an out-of-universe reference. The puzzle itself is both very interesting and fairly challenging. It definitely hits that sweet spot where it's challenging enough to engage the group, but not so challenging as to bog down the game.
All in all, an enjoyable adventure, but could just as well have trimmed to be the beginning of the final adventure.
[3 of 5 Stars!]