That's a truly magnificent piece of work

What yellow? Its so pale I wouldn't have noticed it if you hadn't said it.

IMHO The deserts do look slightly bland, but its very easy to go over the top when part of the beauty of the map lies in the restraint and control of the colour and tone.

Again IMHO - I'm not sure I really like the clouds. I think they are a bit too cartoonish compared to the fine detail of the rest of the map. How about doing them without the line work, but more like a satellite image? I certainly don't think you need any more than you already have

Hope that helps