My daughter graduated from Brown and my son is a current senior at Harvard. From my close observation of the two, Brown is much more focused on undergraduate education, and Harvard is just, well, Harvard. I do think that Brown students get more personal attention from faculty and staff than at Harvard. My son is extremely independent, but even the few times he’s wanted advising, etc., it takes several emails and cajoling to get a response. Some professors never bother to respond to emailed questions and they don’t do regular office hours. He has developed a close relationship with his thesis advisor and a few other professors, but that’s about it. Most medium to large classes are taught by TFs.
As far as rigor, my son took a math class at Brown his senior year of high school, and he says that class was more difficult than anything he took at Harvard freshman or sophomore year. He knows brilliant students and students who he says can barely do the work and take the easiest classes to get by. Any argument that there is less rigor at Brown is silly – it is obvious that most colleges have such a wide range of offerings and rigor is what you make of it.
At Brown, professors seem more accessible and responsive to students, and it’s a closer knit, supportive community. Most people would consider this a positive.
FWIW, all of my daughter’s friends who went on to grad or professional school had great results at the tippy top schools. Brown is very well respected.