The town caters to tourists- golf carts everywhere!
Rent a golf cart if you don't like hills - there are a lot of hills.
All excursions are available on shore easily - don't book through the cruise line, you don't need to.
Submarine excursion is neat, as is the Canyon tour.
A dirty city... not one I would "walk" around in with my family.
Definitely book the blow hole (La Bufadora) excursion from the ship. This was EXCELLENT!
This tour takes off right by the boat port and takes you to the blow hole. There are several street vendors there to sell you trinkets and trash, they are "pushy" but once you say no... it is respected. The blow hole is incredible... well worth the price of the excursion. You have time to shop here and then get back on the bus (a nice charted bus) to go back into Ensenada (they will drop you off to shop more) or stay on the bus and go back to port.
For us, we took the 1:30 excursion and were back on the ship by 5.