Last night I pulled the form off the last concrete pad, painted it, and got the barrel in place.
I realize now that because of where the downspout is located, and due to this different style of rain barrel, I could have used a smaller pad and it would have looked better. Sigh.
I also may repaint it with a paint color that is more the color of the mulch (okay soil) rather than the khaki color that worked so well with the decomposed granite in the backyard...it matches the brick fairly well, but that doesn't really help.
I'd like to add some pavers to try to raise this particular barrel up higher -- I had two layers of cement blocks under it, but I don't think the second one will fit anymore. I suppose I could shorten the downspout to allow me to raise the barrel. I tend to want to use water from this barrel for my front beds, and gravity is working against me as the bed is higher up than the rain barrel placement. Such is life with a sloped yard.
Regardless -- level, stable. An upgrade.