User blog comment:Omega natsu2/Chapter 373: Let Live Or Let Die, Predictions./@comment-7418318-20140226103129/@comment-7418318-20140226104950

That's hardly the first Bankai that is "only" a much more powerful version of the Shikai. Besides with as little time as Rukia had since learning it, I'm sure her Bankai is still incomplete and with a lot of potential for growth.