More like, an 18 wheeler backing down to a loading dock at high speed, then slamming on the brakes at the last moment to time it such that it stops with the back just touching the dock.
The physical engineering feat is one part of outstanding, but consider the software achievements involved. A on board software program that is calculating positional awareness at incredibly short time intervals and controlling not just the throttling of the engines, but gimballing them to drop a few thousand pounds of rocket softly on to the arms. The software that controls the arms to swing in and adjust, also in real time to close at the right moment. That is some serious programming.