This poster was designed for a 3day festival, i love the choice of only 3 colours being used as it tones down the busyness of the illustrations. It also works well against the block fill used on the type for the title, as it adds emphasis making the title stand out. This appears to be a print piece, i think the illustrations of the artists look cool and creative.
The back of the poster works well by just using one colour from the front, it continues on the design in a clean, clear way. It works well to display the information about the festival.