There's plenty of room for simplicity and abstraction, but this is not a particularly good one, if I'm going to be honest. I can't think of any situation in which I'd recommend this over either AFNetworking or the built-in Foundation URL Loading system.
Hiding networking complexity behind a simple interface is exactly the goal of the STHTTPRequest class.
Anyone who needs more flexibility is free to access NSURLRequest directly or to use the library of his choice.
I keep on dreaming of something as simple as the Python's requests module for Cocoa.