I've appreciated the clean bahn.de website and its complete and accurate railway itinerary creation ever since I first used it in 2003. The site continues to impress with additions of comparative travel charts like this one:
It's pretty cool to see how much less impact travel by rail will be compared to a car or airline.While I'm sure more rigorous users have some complaints, the bahn.de service seems much more helpful in getting around Europe than anything else. I must also observe there are no such comprehensive travel solutions for planning a trip in the US. Then again, the only comparable options for transportation in the US are bus and airline – train travel is only possible in certain areas.
In Europe, reservations are only available from the national carriers, so only certain itineraries can be reserved from the Bahn.de website. On the other hand, since I'm traveling with a Eurail pass, it would be necessary for me to make the reservations in person anyway. (It would be nice if the Eurail pass could develop a website for pass holders to make reservations, but I'm sure that's more easily said than done.)