Mug Root Beer is common around here, but until a recent trip to Maine, I had never seen Mug Cream Soda. And after buying a couple of bottles to try out, I think I know why: It's not really that good.
There isn't much body to it, and little flavor other than a vaguely vanilla-like sugar sweetness with a light burnt-sugar finish. It's probably the blandest "cream soda" I've ever had. Totally not worth buying again.