From my quick review: I find the API Console to be cleaner and more intuitive than in the console that’s been replaced. Watching the short video will help you in understanding the basic screen layout and functionality (including the dropdown list with available API keys and the location of the Execute button). The available responses are the request URL and cURL. The code example outputs, available in the previous console, are no longer available.
Usage statistics are also integrated into the new Developer Network site – I haven’t had the opportunity to review this functionality.
Ex Libris will be publishing additional updates on the new Developer Network functionality.