Thermaltake has definitely impressed me with the overall silence of the ISGC-300. The usage of the ISGC Fan 12 is a hit in my book. The real issue here is what you plan to do with the day to day usage of your processor. If you just want to run it as-is or with a mild overclock, this cooler is right for just that. If you are looking to squeeze out every last drop of MHz with whatever voltage needed to accomplish this, I can see the ISGC becoming easily saturated before you get there, making this not the ideal choice. In most instances where absolute silence is a must, there usually is very limited overclocking in the equation anyways.
With an asking price of $43 U.S Dollars I don't think Thermaltake is asking too much for what they offer. As I mentioned, the Noctua is a better cooler in temperature performance and a virtual coin flip on fan performance, but it also requires almost twice the price to attain the Noctua. This is where I think Thermaltake is right in asking what they are for a very silent solution for the masses of buyers out there. If silence is what you desire in a CPU cooler, look no further, Thermaltake offers just that.
Is the ISCG an enthusiast's choice for an extremely overclocked cooling solution? No. Is the ISGC a silent alternative at a good price point? Yes. With that out of the way I will say this; if someone was to ask me for a bang for the buck silent cooler for average use, the ISGC series are the coolers I am going to recommend. I really hope Thermaltake takes this concept and evolves it to different designs and fin arrangements, as I don't think it would take all that much to bring temperature levels down and open themselves up to the enthusiast buyers as well.