DUS is an easy and pleasant airport to transfer through...unlike the dump they call an airport CDG. The LH lounge in DUS is not very exciting, but neither is the *A lounge at CDG. ZRH is certainly one of the nicer European airports.

I don't recall that many shops in DUS, but there are plenty of shops at ZRH although I've always bypassed the shops and headed straight for the LX F lounge.