Depends on sq. meterage, type of tiles, condition of substrate, access, location to name a factors. The fact that it's sloping increases wastage and cutting but it's not a huge factor, you do need to consider the cut edge if it doesn't meet another tiled wall and how you want to cover the edge. If it does meet another wall it can create a bit of a problem lining tiles up.
Depends on sq. meterage, type of tiles, condition of substrate, access, location to name a factors. The fact that it's sloping increases wastage and cutting but it's not a huge factor, you do need to consider the cut edge if it doesn't meet another tiled wall and how you want to cover the edge. If it does meet another wall it can create a bit of a problem lining tiles up.