It's a wondeful, thoughtful painting, in my opinion.
I do have a question for art historians: how much colour drift might one expect from the paints he used? As far as tone scale is concerned, I see no un-reality in the separate halves, but joining them together is problematic. The shadowing suggests a sunrise and hence one expects a rather different blue in the sky- a different colour temperature. Hence I ask whether that blue is the same blue he saw when he put it to canvas.
Regardless of colour temperature, I do enjoy it as a study of unusual contrast in light and statement on how inside light is used.
The idea that comes to me is that a person-secluded in the house, with the light on and perhaps reading a book- is oblivious to the scene unfolding outside. I think the painter wants to suggest that this person is missing the bigger show, so to speak. I get the strong idea of confinement inside the house, versus blinding beauty outside.
Actually, this strikes me as the least surreal of the Magritte work I have seen.