Agreed. Acela is no bullet train. But it is a truly viable alternative to destinations in (on?) Manhattan. I use the Metroliner (usually first class) when I have destinations (as infrequently as I can manage - sorry, Catman) there, and use air only when I'm going someplace on Long Island.
I see that my parenthetical interruptions sort of messed up that paragraph, but I was leading to the conclusion that the Metroliner is a truly pleasant travel experience. If the trip from DC to NYC by train can be made 15 minutes faster, that'll be great. Of course, if AMTRAK doubles the fare for the faster service, that won't be so great.