I would venture a guess that many people do not know what Growlanser is, myself included. They (me) probably don't know what's good or bad about the series and why they should buy it. All I know is that it exists and that I don't like the art. Other than random gameplay videos that I've seen that didn't grab me, that's about the extent of my knowledge.
Beyond the stories(which are really good), the main appeal is the SRPG gameplay. The battles are very tough, and require you to put a lot of thought into your actions, especially if you want to earn a mission complete.
I realize this might be a negative for some, but huge positive for me. Besides, if you don't want to stress yourself out, just go for a Clear or Failure(blech).