You asked, and herewith my opinion:

No, they aren't worth it, or rarely are. Buy point-to-point. Since you rarely can buy cross-border tickets from any individual country's rail network website, and since raileurope is nearly always ridiculously overpriced, wait until you get overseas. The last time I needed a cross-border ticket (Verona - Innsbruck) was last April; I couldn't buy it off trenitalia.com, so I bought it in Venice. I bought it 6 days in advance, but there were plenty of empty seats (travelling on a Wednesday morning). Rail agent sold us a special for two people travelling together - in short, there are deals available that save you money outside of any theoretical rail pass savings. ( I say theoretical, because my idea of a trip is not spending all of it on a train, which is about what you have to do to get a railpass to break even.)

For many trains, you end up having to pay supplements and/or get reservations in additional to the pass anyway, so there goes the so-called 'convenience.'