I should correct the blurb, printed on the back cover and displayed on Goodreads, claiming that Rooms is "part The Shack and part The Screwtape Letters." I haven't read The Shack and so can't comment on that comparison; but Rooms does not resemble The Screwtape Letters at all. The blurb writer made that comparison because a plot point in Rooms is the protagonist reading important letters from someone, but the plot really doesn't revolve around the letters.
In this novel, a rich young software-company CEO in Seattle named Micah Taylor suddenly receives a mysterious beach house from a deceased relative he never knew. Visiting the beach house, he discovers that God is using it to illiminate Micah's true self, restore Micah's long-broken relationship with Him, and transform Micah's life from what it is (great worldly success but lacking any relationship with God) to the completely different life that it would be if Micah had never run away from God.
If you're not a Christian, you probably won't like this novel very much. If you are, you probably will.
As a writer with a degree in literature, I can't say Rooms is any literary masterpiece. The writing style is similar to that of a Left Behind book, perhaps slightly superior. The characters aren't cardboard, but show only enough complexity to let the reader know what their mistakes and their pain consist(ed) of. Julie, Micah's girlfriend and partner at RimWare at the beginning of the book, is a fairly uninteresting character who plays no role at all in Micah's new life away from Seattle (leading her to break up with him). Micah's father, who is the source of much pain in his life, is discussed heavily in thoughts and flashbacks, and speaks in a few phone conversations, but never personally appears and never receives much exploration (other than the narrator explaining why he hates Christians), even after Micah apparently reconciles with him. The author has a habit of unnecessarily giving details of what the main characters are wearing, mentioning that someone is wearing "Nikes" or "501s"; the church friend who introduced me to the book agreed it was pointless and annoying. my knee-jerk reaction is that if I didn't know better I'd think Rubart was doing product placement; but no, he just seems to believe repeatedly mentioning the brand of shoes Micah wears or the brand of soda he drinks constitutes enriching the plot with meaningful. detail. Sorry, no, it doesn't.
As God's way of showing Micah how his old life is built on running from God and how his life would be with a reestablished relationship, Micah's old life as a software tycoon disappears little-by-little every time he gets closer to God, and reappears with similar but not identical circumstances any time he runs from God again and tries to reclaim his old life; this is depicted very much in the manner of history changing in a time-travel science-fiction story. This fascinated me enough that I read the book again mainly to observe those scenes again.