Like others said you make of it what you want. I haven’t taken a class at Bryn Mawr, but I know plenty of people who have taken classes there. I know a History major who takes 1-2 classes there each semester because she likes the classes they offer. Its not really common to take sciences/math at Bryn Mawr unless they want to take an easier class. I’m not sure quite how true this is but even my math prof insinuated that the science classes there are not as tough. Also, some departments are housed on one campus so BMC has theater and dance, Haverford has fine arts and music (Bi-Co orchestra and Bi-Co Chorale) etc…
As for socially, Bryn Mawr girls come to Haverford parties frequently because they don’t have many big parties (there are a handful though). Some people also go there to eat at Haffner (one of the two dining halls at Bryn Mawr) so we can have a change in food options. Some of the items they serve are better than the DC at Haverford, plus it just nice to eat someplace else once in a while. My friends and I go every week/every other week on Fridays for dinner - its kind of became a thing for us to change up the week a bit. Also people go to each others events, especially when there is a more famous/well known speaker. A lot of Bryn Mawr girls, and people from Swarthmore too, showed up when Laverne Cox came to give a speech at Haverford.
I’d have to say the thing that irks most of us Ford (or at least me and my friends) is when Bryn Mawr girls say their chant at the end of a Haverford event/performance. However close the two schools are, Haverford is NOT Bryn Mawr. As for stereotypes, I would say Haverford students tend to stereotype Mawrters as “weird” and “cultish” (because of their traditions). I’m sure Bryn Mawr students also have some negative opinions/stereotypes of Haverford students as well, but I’m not sure what they are.
Overall though, I’ve met a lot of really great people from Bryn Mawr in some of my classes and clubs. The Bi-Co is a nice way to expand the resources students have access to since both schools are fairly small.