Also, by my dangerously semi-informed understanding, B&N's defense looked really weak (see previous comment on same topic: https://news.ycombinator.com/item?id=6540902). I'd still like a real attorney to weigh in on my opinion, though.
So I really don't buy the "B&N scared Microsoft into bribing it" story. To me, it seems more like a "B&N tried a Hail Mary shot at getting an antitrust thing going against Microsoft, and when that failed miserably, they sold a cheap stake in their ebook business" story. Consider that ebook content is something Microsoft's ecosystem didn't (and still does not) have compared to Apple, Google and Amazon's ecosystems. Consider also that this ebook content comes without the lawsuits and publisher-wrangling the others had to go through.
So, $300M for a quick entry into a market where its competitors are incumbents seems like Microsoft got a pretty decent deal, and I think that patent lawsuit provided leverage.
It is OK as long as you have an exit plan/alternative. If you know you can roll your own or switch to one of a number of providers in a week or so and that is a known risk you an can manage it.
Depending on what data you are trusting the APIs with there is also the security risk. CirleCI have just suffered from MongoHQ's security failure in a way that is extremely urgent and customer affecting.
