Should be read with an emphasis on the "me." The original Spanish uses the redundant structure «me parece a mí», which does the same thing: it emphasizes the subject, me, as if to say "everyone else doesn't think he looks heavy, but damn it, I do."

hmm I don't think the "me parece a mí" means that everyone else thinks the opposite, it is just to emphasize that it's a personal opinion, that I may be wrong, not that everyone thinks the opposite :P The Spanish sentence would mainly be used if you don't know him very well, it's your first impression, and to you he seems a pain in the neck. (But to make it softer, you'd use that "un poco" :P you actually can't stand that guy)
Oh! And... wouldn't it be "tedious" or something like that instead of "heavy"? We're not talking about weight, but about (how to say that in English? I'd call "pesado" a person who insists on the same thing once and again and again, and you get bored of listening to him, knowing that he'll tell you always the same thing...)

The English sentence doesn't really mean that everyone else thinks the opposite either. I'd say they're pretty well equivalent.

However, I agree with Shishir that "heavy" should be changed to something else. Using "heavy" in English is kind of stretching the definition. I would maybe say "To me, he seems like a bit of a pain." "Tedious" or "annoying" might also be okay.