Is this university as good as rankings make it seem? Does it stand out in certain specializations in particular?

Washington University in St. Louis is widely regarded as a prestigious and highly reputable institution. It consistently ranks among the top universities in the United States and has a strong academic reputation.
As for their MBA, their programme is highly regarded and holds a strong reputation, consistently ranking among the top MBA programs in the United States. 

It is a very solid choice, particularly when it comes to Finance.