Academics at Northwestern are difficult but manageable. A lot of your experience depends on your major. Anybody who takes organic chemistry is miserable, but that goes for any university. I have had a very light load this quarter, because I am taking a lot of distribution credits and introductory courses. This means larger classes and less personal encounters with professors, but also less work. In the coming quarters, I'll take higher-level courses which are smaller, more intimate and more difficult, but also more valuable.
There is not a lot of competition at Northwestern, at least, not in a negative sense. Students are very encouraging to each other and often meet outside of class to talk about an especially difficult reading or a tricky problem set. I have some friends who actually bribe each other with candy to do their physics homework, which generally works.
Northwestern's core requirements (for most of our departments) are somewhat extensive. We have to take classes in many disciplines such as natural science, formal studies (math and logic), historical studies, values and ethics, social and behavioral sciences and (for most) foreign language. I like this, because it promotes well-roundedness, but some students just despise these classes (called "distros"). However, some of these requirements can be filled by high AP and IB scores, and we have a lot of leniency in which class counts for what. For example, I like science, but I'm not especially good at it, so I used a linguistics class (Sound Patterns of Human Speech) to count toward a formal studies credit. There are usually ways to make these distribution credits double-count toward your major, too. They also do not hamper students' ability to complete majors, because Northwestern runs on the quarter system.
The quarter system basically means we have 3 "quarters" during the school year and one optional summer quarter during which students often study abroad or complete internships if they don't go home. Students typically take four or five classes per quarter, which allows us to take more classes than students at other universities by the time we graduate. Quarters last about ten weeks and culminate in "Reading Week" during which time most classes are cancelled so students can finish paper and projects and study for final exams. (Alternatively, students procrastinate all week and then don't sleep all weekend, which works, too.)
Professors are generally very willing to meet with students outside of class. Northwestern legend Gary Morson, who teachers 600 students Russian Literature most quarters, often makes time to meet with groups and individuals if need be (and sometimes just because). Of course, there are exceptions. My English Literature professor still hasn't returned the e-mail I sent two months ago, but in general, our professors are very willing to be helpful outside of class, and if they are not available, the TA's are.
Majors are generally geared toward practicality and employability. The New York Times recently published an article that ranked Northwestern students as the #6 most employable grads from around the world (as seen by American business owners). Students in the School of Education and Social Policy (my school) are required to student teach or complete a quarter of "practicum" relevant to their major before graduating. Engineering students work on real-world jobs and sometimes co-op. Foreign language and religion classes take field trips to culturally-relevant sites. However, if you love learning just for learning's sake, there are a lot of students here who do and learn things just because, and that's always okay, too. The quarter system allows for a lot of flexibility if you feel the need to sample a lot of different things.