Presently, nothing. Haven't read him for 25 years. When I did read him I had at best a crude understanding of his economics and politics, and much less of his philosophy.
I got enough from it, however, to respect his body of work. And my curiousity has been piqued enough to consider giving Capital another go.
A major disincentive, however, is the apparently endless variations of interpretation. All you have to do is read one of Rakesh's posts to get a flavor of the intellectual chaos among those describing themselves as Marxists or heavy users of Marx.
MBS