I'm seeing weird stuff like [[{"type":"media", "view_mode":"media_large", "fid":"255",... in my imported nodes, where I expect to see images. What's up with that?

If you have the Media module enabled WordPress Migrate will automatically convert HTML <img> tags to media tags, which should render images properly. If you're actually seeing the media tags instead, this means that the proper filter is not enabled in the text format for your node content.

Enable Media Tag to Markup Conversion

1. Go to /admin/config/content/formats (Configuration > Content Authoring > Configure)
2. Under Enabled Filters select "Convert Media tags to markup"