I'm going back quite a few years here to my own experiences but here are a few valuable things I learned...
1) I learned that I didn't enjoy the manufacturing engineering career - and was able to eliminate that from future choices. This is my own personal preference, others may love it, but it helped me decide one thing I didn't want to do.
2) Technical skill - It was a real Eureka moment when I took a bunch of classroom mathematical modeling of how something worked (a transistor in the linear range) and then applied it into a functional circuit. Wow that gave me such an advantage when I got back to school.
3) Real world implications of what career I was pursuing - What will it be like? What kind of people will I work with? Will I enjoy it?