Good point and I had not thought of this. The pin marker will show whether it is uphill or downhill by the arrow. I would also move the marker around and look for any changes to give you the indication over the whole putt. You could also do this in chip mode.
As for the lines I suppose they are no help colourwise. An added challenge for you but it is the actual gradient you should look for so take your time, after all the lines are just an indicator.