After the fix of MC-35658, the top surface of water source blocks is visible again, but the surface of flowing water blocks is still invisible (obviously someone forgot to apply the fix of MC-35658 to flowing water too).
To reproduce it, just place yourself inside a waterfall or something similar. Flowing water WAS VISIBLE IN 1.6.4 !!! I see no reason why it shouldn't in 1.7.x, it just looks weird.