My husband and I stayed three nights at the Park Inn and I would say that it is a standard airport hotel.
The hotel is located just off the autobahn and very close to the airport so you will hear both the traffic and the planes taking off/landing. There might not be much to do in the near area of the hotel, however you can rent bicycles at the hotel and go for nice rides in the country side. There is also a bus stop close by and it doesn't take you long to go down town if you want to visit Dusseldorf.

The rooms are average and I guess it is the standard you expect to find at this type of hotel.
You have to pay for the internet and it is quite expensive if you need to use it a lot. What I thoguht was a bit peculiar was that you also had to pay to use the internet in the business centre which normally is free of charge.

The food at the hotel was good and breakfast was fantastic which a huge selection to choose from. I find it very hard for anyone to find any faults with the breakfast as you have everything you can wish for on the buffet.
We ate both in the restaurant and ordered room service and the quality of the food was very good through out our stay.

The bar staff and breakfast staff were all very friendly and professional. In the restaurant we were served by two very young girls who spent more time giggling to each other so they actually forgot about us (and there were only 3 tables occupied..). The girls lacked proper training and they hardly new the menu and they knew absolutely nothing about wine (we ordered red and they brought us white). I speak fluent German so it was not from a lack of understanding but they were just very young.
The check in and check out took very long and the girl at the front desk was not very friendly at all. During the three nights we stayed we never once saw her smile or greet any of the guests walking by which is a bit odd for hotel staff!
All in all I do recommend this hotel for a short stay or if you need an overnight before going to the airport.