A horrible layout with frequently unpleasant staff (especially security) to add icing on the cake. Heaven forbid you're making a connection and your arrival and departure are from different wings or different terminals. Even if they're both Schengen (or non-Schengen as my recent trip was) you'll wind up going through security at least once. And of course if you don't like the food and shopping options in the arm of the terminal you're in your only option is to yes wade through a security checkpoint all over again! The problem is compounded by poor signage often courtesy of Lufthansa (could someone please instruct them that white lettering on a yellow background is not a readable choice). At one point I didn't even notice I had exited one security zone to enter another until I was almost past it (no sign saying "Leaving secure zone" only a "no entry" sign facing the other way!). When I asked the security officer who saw me there trying to see what the other side of the sign said he forced me to go through the security line all over again if I wanted to turn back! Of course this wouldn't be nearly as big of a problem if each section of each terminal had adequate food and shopping options but all but one of them most emphatically do not. International travelers going through a major hub expect more choices (without a trip through security) than just one sit-down restaurant one coffee shop one news stand and a duty-free! I won't even get started on the small infrequent and hard-to-find restrooms. That said if your destination/departure is Frankfurt the range of ground transport options hotels and car hire makes it quite convenient. For everone else I'd much rather connect through a modern efficient hub like Amsterdam or Zurich!