So what makes the 787 so much better than everything else?
Marketing.
Seriously, it's supposed to be 20% more fuel-efficient, have larger windows for the passengers to look out, and better cabin ventilation; not really a major leap forward (like Boeing's cancelled Sonic Cruiser, which was actually subsonic) but an aircraft targeted to the #1, big-time, all-important overwhelming priority of the airlines:
reduced operating cost.
This aircraft design was driven by the Six Sigma
manufacturing and design philosophy religion of Boeing's new CEO, which led them to do things like build a factory in Russia to make titanium forgings and outsource many of the components - as well as a good part of the design - to
cheaper alternative manufacturers . . . hence the delays and rumored cost over-runs.