German and Dutch are extremely similar. As a fluent Dutch speaker without any formal German lessons whatsoever I can read German pretty well. Speaking and understanding are more difficult, but I'd say most Dutch/Germans would be able to make smalltalk in a bar if they took it slow and used a lot of hand gestures.

while English has germanic grammar, 40% of its words come from romance/french origins, so it really is a mongrel language. Word origins in english are roughly 30/30/25/15 french/latin/germanic/other, with more fancy words ('newspaper english'[1]) from romance and more daily words from germanic.

[1]https://youtu.be/2OynrY8JCDM?t=6m43s - interesting video overall