Unfortunately your beta product of API testing has hit an early brick wall for me. I am unable to use this to test my API's (without manually getting an auth token) because on our internal API the token route ONLY works if the POST body is sent using forms encoded fields. If the content is raw text, the only option for the POST body right now, then our API rejects it as an invalid request, even if it is a well formed json object.
Yes this is our bad and the API should work with a raw text post as well and do some internal validation of the body before it tries to consume it, but being able to just switch the input type like PostMan would allow to do would get us as a test team running quicker.
Something to put on the wishlist - please give us some extra options in the body of the POST and other methods.