I can only speak for his linguistic works, but it's odd how much clearer and more straightforward his earlier works are than his later ones. Syntactic structures and Aspects of a Theory of Syntax are easy enough that I'd even recommend them to Introduction to Syntax students, but starting with Lectures on Government and Binding things get increasingly obtuse to the point that I'd always recommend reading "translations" of his later works rather than the works themselves.

Edit for full transparency, since this comment is getting upvoted while Chomsky is getting blasted in the comments here: Don't get me wrong, all of Chomsky's linguistic work is incredibly brilliant. He single-handedly brought about a complete paradigm shift in the field of linguistics. G&B with all of the bells and whistles added by other researchers in the 80s and 90s is still the closest we've come to an actual explanatory theory of syntax, and X-bar theory is probably the single most elegant, ingenious innovation in the history of linguistics.

And that's just syntax. I haven't even mentioned how he and Morris Halle revolutionized phonology a few years later with The Sound Pattern of English, or how he also revolutionized grammar theory with the idea of context-free and context-dependent grammars the year before publishing Syntactic Structures, and all of this somehow still understates the enormous import of Chomsky's linguistic work.

If anyone has any questions about Chomsky's linguistic work, feel free to ask, and I'll respond as best I can.