This hotel is simple. nothing fancy, yet unless you crave the luxury experience it's very comfortable. Just get yourself a bike (there is a rent nearby at civic 180, the guy's really friendly) and you'll be king of Karlsruhe.
Located in Sophienstrasse, it's about 200m from Kaiseralle (albeit a bit further west from the shopping area in the local shopping street Kaiserstrasse), about 1km from the center. Still you'll feel comfortable, without stressful traffic, yet near enough a tram (strassenbahn) to get to the center fast. The neighbourhood is full of pubs and coffees, easy to walk through, a pinch to conquer if you get yourself a bike.
Biking really lays Karlsruhe to your feet: from Acora it's 10mins to the Kongresszentrum, or 8min to the Schloss. Just 5 mins to Kaiserstrasse or to Waldstasse the center of night life.
All in all I enjoyed my stay in Karlsruhe and in the Acora. The rooms even offer you a couple electric cooking stoves, a little basin, microwave and fridge. You can't really ask for more.