Grand Prismatic Overlook was probably the busiest place I visited in all of Yellowstone, but the view was still absolutely worth it. I went around 10 AM and the area was already extremely crowded, especially near the overlook trail and parking areas. Parking was a little complicated, but not impossible I just had to be patient and wait for a spot to open.
One thing I liked about this area is that there are two different ways to experience it. You can walk the lower boardwalk near the geothermal basin for a closer view, or hike to the overlook for the famous panoramic perspective from above.
The overlook itself is beautiful, but the viewing area is relatively small and fills up quickly with people trying to take photos. It was definitely difficult to get clear pictures without crowds, but seeing the colors of the spring from above in person still felt incredible.