I’ll chime in as a WashU parent. Son is a Biology major premed. The advising can’t be beat because students have a 4 year academic advisor, a major advisor, and there is a pre-med advisor. The academic environment is highly collaborative and students are willing to help each other.
The cons are that the introductory science/math classes have reputations as weeders. Introductory Chemistry is taught very well, but the midterms are tough. The percent cutoff to get an A is 80%, but in some years, 70-75% will be in the B+/A- range.
Organic Chemistry is pretty infamous at WashU. Lots of premeds end up taking it at another school during the summer. Biology majors have that option, but Biochemistry/Chemistry majors do not.
The first 2 Introductory Biology classes could be taught better, although the intermediate and upper division Biology courses are well taught. The Cellular Biology class is an excellent course and the professor (Dixit) is highly regarded.
Introductory Calculus is the big killer-it doesn’t have the greatest reputation. If OP’s son has taken/is taking BC and gets a 5, use the credit.
WashU premed is odd in that Multivariable Calculus is required for Biology majors doing premed. The class is pretty straightforward and most students will get A’s and B’s, but supposedly it has changed so that the class is harder.