Eurail is only for non-European residents, tough. Europeans have to use Interrail, which in turn doesn't cover journeys in your home country (except two single trips if you buy the more expensive all-of-Europe Global pass).
If you want to do a holiday-by-train (and especially if you also plan on doing a few additional journeys while abroad, like a few day trips or staying a few days in one place, then moving on to somewhere different etc.) it can still be worth it, but for a simple back-and-forth journey this means that Interrail passes still aren't necessarily a suitable replacement for true through-ticketing.
(Also some countries require mandatory reservations for long-distance trains which in turn aren't necessarily included in the price of an Eurail/Interrail pass)
