Heidegger is just terrible in my opinion. I was a philosophy major, and I read at least one major work by just about every philosophy any non-serious philosophy student has ever heard of, and Heidegger was by far my least favorite. It really did almost seem like a joke to me... The way he just repeated the same points for dozens of pages in SLIGHTLY different wording... some people think it's great, but he is on my personal list of overrated intellectuals, for sure.
Freud is NOT overrated. Sure, some of his stuff was out there and is clearly not fit for practical application in therapy today, but he was seriously light years ahead of his time, and many of his theories DO still shape the way many therapists work.
Chomsky, unfortunately, isn't overrated as a linguist. I used to think he was such a hack, spouting off his political opinions - and I still pretty much think that, except I learned just how important he was to the study of language. These days, he, like many important thinkers do in their later years, has become a bit of an opinionated spectacle, and perhaps the media's current level of focus on him is too great, but I wouldn't say that his important work is overrated.