Pros: Thor took Groot language as an elective
Cons: the marvel writing team are fucking cowards, only have Thor speaking english and the tree replying in groot, instead of letting that good big buff boy say “I am groot. I am groot? I am groot!” for eleven scenes. Let the man speak. He completed his coursework.
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Also, let the good big buff boy be a bit rusty in his Groot language, say something that makes Groot look at him absolutely insulted, and then a good minute is spent in a “I am Groot!” monolgue – each one with a slightly different emphasis on it – to apologize.