What I liked most about the Thermaltake Element S is the overall design. The removable hard drive cage has plenty of room for 3.5" drives, and the removable PSU cover can handle two more 2.5" SSD drives. Airflow inside the case is good, and the front door panel does a good job of cutting down the fan noise, even with dual 120mm fans installed. The side panels also work well to cut down noise and vibration. Some people may not like the amount of plastic used in the design of the case, but I feel Thermaltake employed it wisely without over-doing it.
However, I think Thermaltake and many other case manufacturers have "raised the bar" and we now expect more built-in features from a case. The main problem I had with the Element S was the lack of tool-less features for the drives and expansion cards, and those annoying metal plates that had to be knocked out before any assembly work could be done. And since I am one of those end-users out there that swap hardware frequently, those options (and a few others) could make working on the case much easier.
The Thermaltake Element S case is marketed toward professionals who do not want a loud case with lots of lights and other distractions. I think Thermaltake succeeds here, as there can not be one case that appeals to every market. Overall the Element S is a great case with a nice feature set.