Well-written and, at first, engaging. No issues with overused favorite words or expressions, free of gross grammatical error, etc. Characters are very well-developed, especially for such a short novel. The author is efficient! However, there is a desert of nothing around the middle of the story where something should be: a hole, rife with possibility, where the reader's imagination must supply everything. The ending is weakened by this, but overall it was entertaining. You can read the whole book in an hour, maybe two.
What do You think about The Alien Upstairs (1985)?