Type safety is the core principle of Querydsl. Queries are constructed based on generated query types that reflect the properties of your domain types. Also function/method invocations are constructed in a fully type-safe manner.
Consistency is another important principle. The query paths and operations are the same in all implementations and also the Query interfaces have a common base interface.
To get an impression of the expressivity of the Querydsl query and expression types go to
the javadocs and explore