I learned Mandarin and Korean, and I agree with you on these, for the most part.
For Mandarin, it depends where you are, but if you're in a big city with Chinese people from all over the country, they'll probably be more tolerant to not knowing the tones. In Shanghai, for instance, you can speak "tone-deaf" Mandarin and people will mostly understand from context. This is ideal, because you can just focus on learning the language until your ear "clicks" on tones. For me, it took about a month, but then something in my brain clicked and I could suddenly understand the tones. It adds a sort of "musicality" to the words, and we have equivalent things in English (such as stress syllable) so it's not that hard.
Otherwise, yes, Mandarin has a really simple grammar, so that part isn't hard. And if you "give up" writing and just focus on communication skills, I'd say the hardest part of Mandarin is vocabulary words that sound very different from English (obviously).
For Korean, Korean's blessing is its simple alphabet. You can learn it quickly and it's hard to forget. The grammar, however, is pretty insane. What I found the hardest, though, is how Koreans use specific "sentences" to say, for instance, thank you... So it's a lot harder to memorize than Mandarin, for instance.
I found Korean easier to pronounce than Mandarin, that's for sure. Mandarin has some funky sounds... Like the "r" that's in-between a r and a j. That one's fun!