Current HTTP activity in flow is very limited in usability as it doesn't provide means to extract attributes from response body. And passing entire response body to other web request or other activity is so to speak useless. So there should be means provided to extract parameters from three most typical http response types:
1) From XML as Xpath
3) From text as simple regex (like in transport rules in Exchange)
That would make flow 10x more usable and give it competitive advantage over IFTTT. Most datasources don't support swagger yet, and making swagger proxies requires much effort and infrastructure. Support for above scenarios would allow pass parts of responses from one web requests as parameters to other web requests giving people plenty of new scenarios available on Flow.