My experience at the Steigenberger Hotel in Stuttgart was good. The location is conveniently right opposite the main train station, and in a walking distance to the main shopping street.
The room on level 5 (the highest at the building) was surprisingly (for European standards) spacious, the bathroom a bit small though. Breakfast was superb - maybe this is what I sometimes miss at Asian hotels given that I like the German style breakfast with a lot of choice.
Conference room facilities were good and plenty of them available. Therefore, the hotel is certainly good for business events.
Staff is very helpful but not particularly friendly.
The downside of the hotel is that they do not offer frequent flyer points - at least not for the rate I had and which was already over EUR 169 which I found not that cheap. Maybe I am used to Asian hotel prices and comfort, and have forgotten how expensive German hotels can be.
Overall, a pleasant stay though.