I'm not sure what I expected from a mattress that is only 8 inches, but it is NOT ultra plush at all. It is very firm. I was very surprised by how firm it was. I was initially concerned about the opposite, it being not firm enough, but it's actually too firm for me. I love the mattress aside from its firmness, it's a great mattress, but it is not ultra plush at all.
I highly recommend getting the 12 inch option instead, that might actually be ultra plush, but the 8 inch option is not. It is so firm that I just bought a foam mattress topper for it.
Still, aside from it's firmness, this is an excellent mattress, but I wish they wouldn't call the 8 inch option ultra plush. I really do like it, but I don't like how firm it is. It did expand to its full size, just in case you were wondering, I had no issues with that. It also had no odor. I let it sit and expand/air out for 72 hours before use just to be extra careful about letting it expand.