Good questions, and a good place to start. I came into my first year expecting to have my mind blown. I approached it with the idea that the human body would start to become demystified. I wanted to go to medical school, of course, to eventually "help people". But to do that, you first have to learn, to soak in knowledge, to put down any barriers you have and march into the unknown.
Every day, I learn so many new things. Every day, I sit in the lecture hall or at my books and am completely amazed by not only what I am learning, but by the fact that I have the opportunity to learn it. I volunteer in a clinic with M1/M2/M3/M4s, and it boggles my mind to see how much the fourth years know. And how much the third years know. And how much the second years know. And then it boggles my mind even more to think that I will be in their position very soon.
The amount of information you learn really cannot be understated. You've all heard the "like water from a hose" analogy. I'll give you another one. The four months that I've been in medical school feel like YEARS. We've been learning so much about so many parts of the body, from anatomy to physiology to biochemistry. We've learned history taking and some of the physical exam. Every week, I don't just learn new things about the human body -- I completely redefine the way I see the world. I feel myself making that transition to seeing the world from a doctor's eyes. It's one hell of a process, and it starts again every day.
So to actually answer your first question, I didn't know what to expect from med school in terms of the day-to-day (I can get into more specifics about that if you'd like); I had more of a big picture expectation in mind. And it's been met a thousand times over.
And to answer your second question, literally every day is a pleasant surprise. Cheesy, but it's absolutely true.