Beauty is in the eye of the beholder; and what standards you measure against.
Using the 15 minute DOT standard, Acela did well on the WAS-NYP leg (93.3%), but worse on the NYP-BOS segment (80%). Is this good enough? I submit that an even tougher standard is called for, the one used by the nation's busiest commuter line, the Long Island RR, which considers any train reaching its terminal more than 5:59 behind schedule to be late. I favor this standard because it reflects what business travelers expect; the LIRR delivers, overall generally between 90% and 95% OT.
Using the LIRR standard, we get OT rates of 73% and 40%, respectively, for the WAS-NYP and NYP-BOS runs. Obviously, there is room for improvement. I suspect congestion may be the biggest problem, but better dispatching can help, but it is difficult to plan for contingencies, i.e. the local in front taking too long at a station. Amtrak could build in more wiggle room, but that leads to diminished expectations (remember, the 20th Century Ltd. took 16 hrs. to do NYP-CHI; the Lake Shore Ltd. takes close to 20.) Does anyone know how they do it in Europe and Asia?