TC Eelectronic tends to build pedals with good quality and very reasonable price tag, and this is no exception. What has been perhaps slightly botched is the marketing. When buying a Dark Matter distortion, you might expect some ultra-heavy, senseless gain range core / djent capabilities out of it. Instead you get something that may suit more in the 80s style sounds with pretty moderate gain.
The pedal itself is well built, has very decent amount of control over sound, and most importantly the gain structure itself is good. It plays nice with other gain type pedals, both boosting others or getting boost - there is headroom into it. But, like said, by itself especially it has its limits in how "heavy" a sound you can produce with it.
Personally it ended up recycled after a couple years of infrequent use. On a clean channel it didn't produce sounds I was particularly after, and used as a boost for dirty channel or other dirt pedal it did pretty good jobs with my tool combinations, but I had the same or better effect with another solutions and pedals.
For someone who's new into a world of moderate gain distortion, definitely get this; it is versatile, well built and cheap, and you can get a lot of mileage from it as a low gain boost pedal even after you've found your THE distortion unit. This is also a good option for turning about any amp into something in the lines of 80s Hard Rock / Hair Metal machine. Just don't expect a gain monster straight out of the box due to the name of the pedal.