This is a great prelude to introduce a party to the Tomb of Annihilation storyline before the book picks up. It does require a bit of attention to make sure that you keep it consistent with the presumed timeline prior to the proper hardcover introduction.
For me, it also required some on-the-fly tweaks to the story to help suspend the disbelief of my players that a lich would have a "secret" back entrance that a group of 1st level characters could break into. In this case, the twist was that her phylactery was actually a decoy and not the real deal. The players panicked as they had no leverage over her and were prepared to try and flee before the Harpers appeared with the real phylactery - they had used the raid as a distraction and ruse to hold the lich's attention while they stole the real phylactery.
Suspension of disbelief issues aside, this is a very nice mini dungeon crawl, even if used outside of the ToA story.
[4 of 5 Stars!]