There's not a lot of information about this mattress on the web. Sleep Innovations doesn't even list it as a product they manufacture, so it must be a Costco-only thing.
It comes in a box, vacuum packed, to your door. The cover is already on it, unlike many other foam mattresses (that you have to wrestle to put the cover on). Just unroll it on to your bed, let it fluff. It needs 4-8 hours for the creases to get most of the way out, and should be fully restored in a day or so (yes, you can sleep on it before that, and it's fine).
So first of all...
It's huge. At least compared with the old dead 6-inch inner-spring mattress that it's replacing.
It's amazingly comfortable. Lie on it, and you just sink into the surface just a bit. Move around and the whole mattress doesn't move with you. It's just amazing.