Everything is nice and close at Universal. We rarely used the transportation from the hotel to the parks since it was faster to just walk. The parks are on either side of City Walk and everything is very walkable.
We stay onsite and walk everywhere...the only time we used the transportation was to change it up. It's all very close together and the way they have it landscaped it's a pleasurable walk.
The only exception would maybe be the PBH which has the longest walk. Then the boat or a rickshaw (I know I mispelled that) would be nice.