All of your illustrations and maps are great, they're charming and legible.
I like how varied you made the swamp, each of the areas is clearly defined. I like how you broke up area descriptions with the most important details expanded on.
I would recommend labeling the notes under Encounter Table on page 1 as "A, B, C, D" instead of "1, 2, 3, 4", since there are already a lot of numbers there.
The background image you used could be more faded, or even better just white, to improve legibility and printing - I think it worked best on the map page, where it added a bit of character in case the GM hands it out to players.
The NPC descriptions were great, providing just enough info, especially for the Rival Adventuring Party. There's already a ton of useful content, but it might be interesting to see Thelka's Lair expanded with a dungeon layout.