Played Dungeon Monsters a bit, and it's a fun game that reminds me a lot of the TG-16 "Double Dungeons" (Except for the title screen which screams "Dungon Master" )
Basically a bare-bones random maze with monsters and gold and an exit to the next maze. Plays fast, very responsive controls.
Biggest thing to note is that it's realtime - if you leave it sitting the monsters can attack you!
IMHO I'd love a true turn-based mode: literally you move/they move/etc. Adjust the damage amounts UP to compensate.
Another simple addition that would add to the game would be a monsterless/goldless "Maze Mode" where you simply find the exit as fast as you can (like another of Alexandere's apps, I forget the name.)
Not sure if there is sometimes a key to unlock the door, but that would be a great option for later levels.
Also also (thinking "Double Dungeons" again here) since the iPhone version uses a small screen (like the watch) it would be truly awesome if you put another one of those facing the other direction so two people could explore the same dungeon, competing for gold, moves to the next dungeon when both players get to the exit.)
Overall a simple, but solid dungeon crawler which should be fun even on the watch.