When Utterson meets Hyde in Chapter 2, Utterson is completely repelled by Hyde. His reaction to Hyde can be fairly neatly summed up in one line that Utterson speaks. He says to himself
God bless me, the man seems hardly human!
and then goes on to say
...oh, my poor old Harry Jekyll, if ever I read Satan’s signature on a face, it is on that of your new friend.
Utterson cannot really understand why it is that he dislikes Hyde and is so repelled by him. He thinks about how Hyde looks a little bit strange and about how Hyde sounds strange. But he thinks that these things are not enough to account for how deeply disgusted he is by Hyde. He wonders if he just hates Hyde for no good reason.
Utterson does not realize it at this point, but what he is seeing (and being repelled by) is the fact that Hyde is purely evil.