If you leave university and work in M&A or capital markets for a major investment bank, you'll work long hours. But you will also earn a lot more money than your peers: in the US, total compensation (salary plus bonus) at major banks ranged from $135k to $205k for first year analysts last summer; in the UK, some banks are now paying analysts salaries of £70k, plus bonuses. This helps negate the pain of 80 hour weeks.
But what if you're working long hours for a fraction of banking pay? This is the gripe of juniors in Big Four (KPMG, EY, Deloitte and PWC) accountancy firms, where the hours can be long and the pay can be lean.