Undergrads now have similar competency in writing as they did in the late 80s - early 90s, but probably make different errors. Grammar is probably in a state of flux - ignoring textspeak completely, I think it's fair to say that "they" is well on its way to becoming the third person singular pronoun of choice for talking about humans without suggesting gender. In another century, perhaps, it will be accepted, but it's here right now and we can just decide to get along with.
Since there is no course for (or evidently even organized study of the pedagogy of) my field, I took the pedagogy of writing a while back. Quite an eye opener. Grammar and Spelling aren't even a goal now - the idea is they'll eventually pick it by reading enough. Also gone - pretty much any style of discourse other than the research paper, anything handwritten, and the reading of literature.
Meanwhile, the level of mathematical sophistication has increased. When I was an undergrad, it was unusual for students to come in with any calculus. Wealthy school districts could afford AP Calculus, and the rest of the state ended at Algebra IV. Now they can take AP Calculus online. Sure, it's the "AB" class, it's only good for one semester, but it makes a big difference in terms of graduation rates and time to degree.
Also, and this is purely anecdotal and shouldn't be trusted, but kids aren't coming to class wasted. I'm not saying they aren't using, I'm just saying they aren't coming to class blasted into space.