I haven't read the novel, and yes, Theroux is generally a good writer, but I'm not really seeing the point of writing a novel about Orwell's time in Burma. It's not like Orwell hid this part of his past -- he wrote a novel of his own (Burmese Days) influenced by his time there, and some of his more famous essays e.g. Shooting an Elephant deal with his time as a colonial police officer.