The ability to apply theoretical knowledge to real-world situations, it was incredibly fulfilling.
What I wish was different
My boss didn't establish expectations for the frequency with which we would communicate and did not have any sympathy for the fact that I was enrolled in summer sessions 1 and 2 at UCSD.
Advice
Go in ready to ignore a lot of what your classes have taught you – I thought the world of sales and marketing was going to be similar to how it was described in textbooks and lectures, but there are so many nuances that render 50-75% of that information irrelevant.