Better graphics, better story, weapons that work, less repetition, better AI, more atmosphere, interesting characters, things within that world functioning as they would in such a post apocalyptic state, Etc. It comes down to a matter of opinion, but Metro 2033 has received much better critical acclaim. Open world doesn't = better, in many instances, including stalkers, it just made the game get stale before the ending. Metro 2033 has a modding community as well, but nonetheless I was referring to the game in its vanilla state. (Game is closer to about 10-11 hours long if you actually explore and take in all the dialogue of the game, plus has multiple endings.) Once again, comes down to personal taste.