Over the years I've tested a couple of different laptops with several different notebook cooler devices, and one thing seems to hold true. That is, whether or not the cooler actually helps to cool internal system components, as opposed to just keeping the bottom of the case cool, depends highly on the design of the laptop. Not only the path of the airflow and where vents are placed in the laptop case, but also how efficient the stock cooling system is and how much heat the components produce. So which make and model laptop you're using is going to greatly affect how effective any cooler you choose will be.
Unfortunately for me, neither the Thermaltake Massive23 CS or the ST do much other than look good. But the same might be said for any laptop cooler. With the ST's plastic construction, weight is reduced by nearly half compared to the CS, however the underside of the cooler has uneven, rough edges that are uncomfortable when used on your lap and more easily snag on fabrics than the aluminum frame of the CS. On a tabletop it does make for a nice base, the rubber anti-slip feet keep it stable and the slope of the base tilts the keys towards you at a slight angle. Just as with the CS, you have to be careful with placement of the ST cooler so that airflow to the fan is not restricted by the surface it rests on.
The blue LED lights are a bit of a gimmick, once you set anything on top of the cooler you'll likely never see it except on a desk or table in a dark room or at night by what little light comes out the bottom. The lights are brighter on the ST compared to the CS but still not readily visible in a brightly lit room. Using it on your lap or carpeted floor not only potentially blocks airflow to the fan but also the light as well. Of course, if you're using the Massive23 ST on a desk or table, you've likely got the laptop plugged into AC, and battery life doesn't mean much at that point.
The Thermaltake Massive23 ST retails for $40, which is $20 less than the CS version. Unfortunately the ST feels like it's even cheaper. Although using the same overall design and benefiting from its plastic construction resulting in nearly half the weight. I have a hard time recommending the Massive23 ST for using on your lap, if however you are looking for an inexpensive notebook cooler just to use on a desk or other hard surface, the ST will function just as well as the CS and save you some cash in the bargain.
Cheap plastic frame
Fan intake easily blocked
OCIA.net has awarded the Thermaltake Massive23 ST our Bronze Seal of Approval.