The Kaverian Motel is a good close-up on the quality slippage from the core five to the final three maps. The roof vents on earlier maps were drawn to show the angled fan blades recessed inside the housing. These are much more abstract (circle, x, +, done!), and the inkers didn't even bother to color the chimneys black on the interior. The clusters of tiny shops that gave the early blocks character are mostly replaced by much larger buildings with fewer features.
Notably, the last three maps came out when TSR was being run by Lorraine Williams, the Buck Rogers heiress who forced Gary Gygax out and spent most of her tenure cutting costs, laying off staff, pushing out untested products with sometimes questionable production quality, and trying to milk the Buck Rogers property for a few more bucks. (She reputedly hated games and gamers - not a great fit for CEO of TSR.)