Hi,
I've stayed at the Ibis Centrum on a number of occasions. As the hotel is based away from the centre of Krakow in a residential area, you donnt get many views. You'll either get a room facing an inner courtyard so all that you will be able to see are rooms opposite, or else you'll get a room facing the streets surrounding the hotel.
If I was you I would e-mail the hotel and see if you can get a room on one of the top floors, (6 or 7), in the direction of the Vistula River. From here you should be able to get views of the Castle across the river.
Hope this helps.