I stayed here about 6 years ago and remember then not being overly impressed. As I travel to Essen a lot, I thought I'd give it another try. Nothing had changed.
If you just need a place to put your head down, maybe do a bit of work, and freshen up, then it is fine (I wouldn't stay more than two nights though). However, you can do the exact same in many other hotels close by for a lower price. The only real plus, is the breakfast. The choice is quite good and the view is great :-)
The only staff interaction was the guy checking us in and the lady checking us out. Both were very friendly and efficient.
I have two main negative issues with the hotel:
1 - You need to be fit. Our room was about 3/4 way along the corridor. From reception to the room is probably the best part of half a kilometre or more! I would hate to think how far it is to the rooms as the very end.
2 - It has no soul! This may sound ridiculous, and is not something I've ever felt the need to write before. But it is how this place feels. There is no sense of warmth, welcoming or personality to it. Rather it is just functional and cold.
Will I stay here again? Probably at some stage because there is nothing wrong with the hotel as such, but I won't be rushing back.