Depends on the person and the degree.
Around 13% of student on my course come out with 1st class degree, I know I won't be one of them.
I tend to score very highly on assignments and lab assessments (70-80%+) but really fizzle out on exams. Though my exam scores have improved each year they really let down my overall mark and I always end up with a 2:1 overall. Whereas I have friends who are the opposite, struggle with assignments and assessments but ace their exams. So yeah, pretty sure I'll get a 2:1.
Cambridge at number one