Honestly, even though I'd seen it in photos hundreds of times, seeing it in person was a completely different experience.
First of all, the whiteness. It looks faintly pink when hit by the morning light, and it's amazing how the expression changes depending on the time of day. It didn't just feel like a "big building," but rather like the whole atmosphere was designed.
Up close, it's surprisingly delicate. The intricate marble decorations and the jewel-inlaid patterns (inlaid work) are really meticulous, to the point where you think, "Was this really made by human hands?" From a distance, it looks perfectly symmetrical, but up close, there are human touches in the details. That contrast was impressive.
Also, I think I understand a little why it's said to be a "symbol of love." This is the mausoleum built by the Mughal Emperor Shah Jahan for his deceased wife, Mumtaz Mahal. It's also a display of power, but more than that, it was a scale that made you feel a "level of obsession" in his love.