Reading this poem sounds like trying to talk with your mouth full of some ridiculously rich dessert. There's just so many words, so much to chew on, that we have a hard time taking it all in. At the rhythmic level, there is a lot to digest. That is, there are lots of hard, stressed beats, often in a row. For example, the first two words of the poem are both stressed: Flood-tide. After that, Whitman never really lets up. Check out the number of stresses in this phrase: "The sim-ple, com-pact, well-joined scheme" (7).
Then there are the large number of lists and repeated phrases throughout the poem. As soon as you get through one set of lines that all begin with the same word ("Others […] others […] others"), you come to a set of lines that all beginning with another word or phrase ("I too […] I too […] I too […]). You're constantly "chewing" on these long lines, never really having the time to catch your breath.
Whitman chooses a lot of his words for their onomatopoeic effect – because their sound contributes to their meaning. These words sounds like some strange, involuntary noise you might make while eating a huge feast (we know, we're charming the socks off you, right?). "Blabbed, blushed", "scallop-edged waves," "mast-hemmed Manhatta," are all examples of Whitman's love of unusual-sounding expressions. The language is as dense as a triple-fudge cake with ice cream on top. And then, when the speaker returns at the end to recap all the sights he has seen, it's like getting a big second-helping that you're not sure you needed. The lists seem to go on, and on…but it's so fun to say out loud that you don't want to stop until you're finished.
"Crossing Brooklyn Ferry" is a big meal, all right. But like those wonderful "things" at the end of the poem, those "faithful solids and fluids," it might just leave you "insatiate" for more Whitman to chew on. Fortunately, you can always help yourself to hefty heaping handfuls of Leaves of Grass.