You are going to get great sound that is tight, well controlled, and extended in a small box. A high SPL monster it is not. But it is not very expensive either. While it isn't going to give you quite the control or high SPL of one of our servo controlled systems, it is also about half the price.
At only $327 for two 12" subs and an amp, if it doesn't give you enough output, then add another amp and another pair of woofers. Dollar for dollar it still might give you the most output for your money.