You are what you API
The majority of my time has been spent enduring APIs from Google and Microsoft. So many hours of my life have been stolen by these terrible interfaces that I can't quantify the lost productivity and frustration.
Hoops for the sake of having hoops. More calls when there could always be less. Things that are supposed to work don't. Cryptic documentation if there even is any. In Microsoft's case they explicitly try to prevent you from integrating with their services over ActiveSync. They literally only published the documentation that you can find as a result of a court order.
GData is an unmitigated disaster. It is the basis format of many of Google's service APIs. GData is based on a notion of data feeds using the Atom format from 2005. When I try to interact with Google it feels like turning the clock back a decade.
Google over-engineers its data in every conceivable form. They deprecate simpler APIs for more complex ones. APIs are inconsistent from service to service. Some use GData, others don't and some vary the way in which they do use it. In an effort to solve any data problem they ensure its always painful for whoever is trying to use it.