I've seen worse, but I wouldn't describe signage at FRA to be "good". What's missing, in particular, are clear signs telling you to turn left or right. I would expect to see signs with a left or right arrow before the left or right turn, but find they're quite often positioned after the turn (i.e., overhead the corridor you're meant to be turning into), so unless you happen to be looking left or right you will miss them.

So, advice to the OP... whenever you come to a junction always make a point of looking left and right, just to make sure that the corridor you're about to cross isn't the one you're actually meant to be turning into.