To Start with , not too bad.Well connected by Train.Just that the airport is too much crowded.Since this is International airport , you need long lead time.This is what sucks comared to the nearest next airport Koln(COLOGNE).I am a frequent traveller to London and I prefer Koln to Dusseldorf.Eventhough Dusseldorf airport is 10 times bigger that Koln aeroport. Koln is 10 times faster for flights to Destinations in Europe.
Believe me Cologne airport is 10 times better and faster for busy people.If in case you are left with nothing to do then Dusseldorf airport is a better one.Got lotz of Cafes lots of things to do inthe airport etc.. othewise I prefer Cologne for Destinations in Europe.
Otherwise, lets say you are travelling to some parts in Asia- Say India, you would have to transit some where in Middleeaset.Well currently there are no direct flights to India from Dusseldorf.For this you will have to go to Amsterdam or Frankfurt or Paris.I prefer Frankfurt, because there is this ICE that takes to frankfurt airport in 1 hr from Koln.Believe me in 1 hr u are in Frankfurt airport.It maintains a speed of 300 KMPH on average.and this train is PUNKTLICH.