Problem is that it has to be injected very frequently, many say everyday. That's probably too much for a beginner. The shots are also painful. Few people would use suspension for long periods, because of the painful frequent shots and other reasons such as sides. Mg for mg suspension will have more sides than any other test. For starters, it's stronger mg for mg since it is plain crystallized test with no ester attached. Also it's a very spikey and obviously quick release.
The reason you've never known anybody who has taken it before is that it's pretty hard to find as very few companies make it these days. Fact is that it's made basically for bodybuilders and that's that as it's very impractical for medical uses.
Again though, it's not all bad. For instance, suspension is probably the best gear in existence for increasing workout aggressiveness, most say even superior to methyltest. Its effects can be felt within a few hours.
All in all though, I'd have to say that Masteron and suspension are both poor choices for a beginner. Both are drugs that bodybuilders tend to use for short periods close to contest time. And yes, many do use suspension fairly close to contest time in combination with anti-estrogens.