Yeah the Amtrak passes suffer from the problem of too much complexity, which makes them risky for the buyer. The restriction to only 4 trips on any given segment is especially killer. Their own example shows that going from DC->NY and back would use up 2 trips, then DC to Philadelphia would count as trips 3 and 4 because it happens to travel the same segment of track for a while as the DC->NY route. That is way too hard for the buyer to figure out on his own.

I wish they still offered the unlimited riding for 30 days passes that they had several years back. Eurail passes are immensely popular, partly because they are easy to understand.