Ovum's blog about that topic is particularly interesting.
Do you assume the risks of using proprietary plattforms ?
Keep in mind the following points about using proprietary plattforms:
* lack of assurances regarding the continuous provision or reliability of the service or that it will remain available for free in the future
* lack of control over the content displayed by the vendors on the platform - particularly advertisements
* lack of control over how the vendors use data that is provided by agencies
* the requirement to indemnify the vendors from any claims arising from the agency's use of the service.
* service interruption or unexpected termination
* inappropriate information or advertising being displayed on a map
* confidential information arising from the delivery of the service being used by the vendor in an inappropriate manner elsewhere in its services
* the agency's brand being used in an unwelcome manner
And of course, data behind these services are never open and can be used only with the terms of services.