As for what they're trying to accomplish... it sounds like a slightly different version of the AGPL (in spirit), and while I'm not the biggest fan of the AGPL and similar licenses, it's not the abomination that the Common Clause stuff was. This seems to just be saying "if you want to offer a MDaaS (MongoDb as a Service), you have to release the source code to the entire service". It's probably not a license I'd choose, but it's not exactly unreasonable.
Disclaimer: I haven't read the entire license yet, so my comments above are based on other people's summaries / the text of the article linked above. My opinion is subject to change once I've had time to digest this fully.