After 2 weeks on the road for vacation, sleeping in 7 different hotels, this was by far the worst experience! The hotel is completely dated. Check-in was slow, with a bunch of forms to fill and sign (even if the booking was already pre-paid).
The first room they gave AC was not working, after calling reception asking to change room we needed to wait 20min just to the attendant verify that the AC was for sure not working.
Furniture is old, no double beds, no power plugs near the bed, no welcoming amenities (like a free bottle of water, etc..)
Breakfast products were not fresh, the bread looked like from the day before.
This is NOT a 4-star hotel.
During the same trip, we stayed in cheap 2-start road hotels that were much more comfortable, welcoming (a lot gave FREE WATER BOTTLES), and new than the NH Viernheim.
For luck, it can be classified as a 2-star medium hotel.
Please, don't be deluded with the 4-star classification, you can look for other hotels with less classification in the same area with a better service.