An English-speaking person learning Dutch learns that a high degree of competence is required for usability. You can't use the language unless you speak it relatively well.
"English is so easy," he said, "because it's basically simplified French...."
This is why the language has a reputation as especially difficult, I think and maybe especially amongst anglophones. I met a Polish guy at a cafe in Seville, and mentioned off-handedly (in English) that I'd heard Polish was a difficult language to learn. He said, with some authority, that "every language is difficult to learn."
Spanish is easier to learn than Dutch, because the Dutch speak English. One must first work to merely conduct simple transactions. For more complex interactions and relationships, English will be the common language until you're proficient.
This makes learning Dutch in the natural fashion a slow process.