Perhaps I'm doing something wrong, but whatever it is, it works for me. I still don't see any advantage to putting a second-rate (they're never as good as the real thing) terminal into an IDE. Someone mentioned project-specific completions, but I can't say I've ever needed the terminal to do that, and I generally don't run IDE-specific tools (also mentioned) from the terminal either.
Maybe my natural workflow gels better with how Apple envisioned people using the IDE, perhaps I happen to be on the "golden path", but ... again shrug. Works for me.