IMO... The bag in the pic above looks like it was just pulled from its storage bag or possibly a stuff sack. I have a Plasma 15, and trust me... it puffs up! Way up!! I have owned WM bags for over 10+ years (Ultralite, Summerlite and Highlite) and the Plasma is superior in nearly ever way. This is most evident in the hood, draft tube and neck collar. The Marmot design leaves the WM bags I have owned in the dust in those areas, offering far greater comfort, warmth and ease of use when cinching down the hood and draft collar. The Plasma hood coddles your head and nothing touches you in the wrong way. In contrast, the WM hoods are very shallow, do not coddle your head nicely, the velcro often lays against your face and the cord in the draft collar in the Ultralite lays in such a way so that when it is cinched, it literally presses down against your neck and throat - very uncomfortable! The Pertex fabric in the Plasma also feels better and is far more water repellent than the Extremelite fabric from WM. I have also found the Plasma 15 warmer than the Ultralite, so I'd also say the 15 degree rating is pretty much spot on.
Now, I love that the WM bags are still made in the USA, but after trying the Plasma 15, I knew I had found a superior bag. Yes - it weighs about 2.5 ounces more than the Ultralite, but I'd gladly trade those few grams for a far superior sleep. Also - I don't think Marmot's goal was to make the lightest sleeping bag for temp rating on the market. If that was their goal, they failed. I think, rather, that they wanted to create an absolutely full-featured, top-of-the-line sleeping bag with most, if not all the bells and whistles, and do so at a weight "nearly" the lightest in each class. In that regard, I think they hit a home run! Again... IMO... :)