The room shown on your cruise documents is the room to which you have been assigned. There are usually no changes from what is on your tickets.
Is your room the same category for which you paid? Or is it a balcony room in a higher category? A guarantee means that you'll get the category for which you paid or a higher category. It all depends on whether other people on your sailing have actually paid for higher categories, how many empty cabins there are (holiday sailings are usually pretty full), etc.
That being said, a balcony cabin in any category is going to be terrific!