Like Carol said, most of Illuminations happens close to the water so you can't see much from the Boardwalk area. DW and I did stroll down to the end of the BW near JellyRolls and could see some of the fireworks, including the finale.
DISPOP, you didn't ask but we did have a room with a very nice view of MGM Tower of Terror. At night, we could clearly hear the Fantasmic music and see a little of the fireworks there. It was cool to sit out on the balcony, listen to the familiar music and hear the roar of the crowd at the end of the performance.