Be aware that the consensus over on the UA forum -- based on experiences since 11/4 on domestic 787 flights -- is that the 787 is roughly on par with existing airliners in BusinessFirst (i.e., nothing special), and generally worse in economy. Ambient pressure/humidity, engine noise and overhead bins are genuine but minor improvements; windows are mixed (bigger, but the LCD "shades" can't fully darken the cabin for sleep)... but the Y seats are slightly hard and very narrow. UA went with the same 3-3-3 seating config as on the 777, on an aircraft that's 16 inches narrower. And when it comes right down to it, seat comfort and personal space trump almost everything else on long-haul.

So, in short: do it for the novelty, but don't expect a better ride.