I bought the blue bubble bowl originally to just have a second bowl and to match the Stax Blue Glycerin piece I also bought. Both are phenomenal. The chiller cools the smoke significantly and the bubble bowl was an even better, unexpected, addition to my STAX rig.
The bowl is a little smaller in capacity than the standerd cone bowl that comes with both pieces. This makes it ideal form single smoke session for myself. The cone bowl holds a large amount and is great for groups or individuals. Sometimes I just like a smaller bowl so the bubble bowl perfectly did that role.