We were lucky to have a private tour with just the two of us. The tour gives you a chance to see the coast from another view, while having fun, learning some (fun) facts and where it is nice and quiet (in contrast to Amalfi itself). Our guide (Antonio) spoke fluent English, was very easy-going and in addition also gave us some tips for the rest of the visit in Amalfi.
The site says that it is reachable by foot taking a nice and short walk. We did this and the walk was not so nice because of all the cars. There were a lot of stairs to take, which was fine by us, but if you don't like taking stairs we would recommend taking the boat, it is easier and not expensive. Going down the stairs is one thing, but going up is another thing so we took the boat back after the tour :)
We definitely recommend it, it was worth it (even if I was a little seasick).