Well, as a native speaker I don't really have first-hand experience to how hard it is, but here in Belgium it generally agreed on that it's easier for Flems (Dutch speakers) to learn French than for Walloons (French speakers) to learn Dutch. And past tenses of verbs in Dutch are absolutely borked, so much so that this past weekend my sister and I (and we're both quite well read) had no idea what the past tense was of a word, though which word it was escapes me at the moment.
