These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Narm: Some of the dialogue, especially Lisa's, is this, although it could be justified by her major insecurity issues.
Romantic Plot Tumor: While it doesn't take over the story, the romance which is kindled between Lisa and Julian does seem to come a little out of nowhere. It provides a nice bit of human drama and a shelter from the unrelenting suspense, but less charitable readers might consider it a case of Strangled by the Red String, or at the very least an unwelcome distraction that breaks the narrative's momentum when it should be moving into the climax.
The Woobie: Gladys/Gracie Ella. If her ultimate fate doesn't make you feel sorry for her, reading her letters, learning the backstory from the clippings, and coming to realize what a hold Chamberlain had over her, will.