Herculaneum really is a neat place. The area is compact, at least compared to Pompeii, and below the ground level of the surrounding town/apartment buildings. You could walk through there and really get a sense of what the place was like. Very well preserved. Of course that was quite a few years ago, so maybe it's changed a lot. Then again... cogs turn slowly over there, except on the roadways.
Pompey is like a big park full of ruins (I don't know how I walked/waddled through that place 3 days before my son was born, just crazy lol). It's nice, but ruins all start to look alike after a while. Herculaneum has always stood out as impressively different from the usual piles of ancient rubble.