I wouldn't dream of trying to speak to her impact beyond my own personal experiences.  I spent most of the last 2 1/2 years jumping around between Miki 3 and 4, Alyson 2, Antonia and MyMichelle.  I found things to like about all of them, but I found a major stumbling block for all of them, a real lack of content.  I prefer buying my content as opposed to trying to make it myself and each month I would click away from stores with either minimal purchases or no purchases.  It wasn't fun anymore, when Alyson's 2nd Halloween and Christmas rolled around and I still didn't have either a zombie or any angel poses for her, well disappointment didn't begin to cover it.  So this past Spring I closed Poser and quit trying to shop or bothering with rendering.

 

Dawn has changed that for me.  She is easy to use and the appearance of content has been reasonable for a figure that didn't come from Daz, I can only hope it continues so that I continue to have a reason to browse the shops.  As has been mentioned before, more morphs and expressions would be nice, but you know, I have Dawn's Starter Morphs, Mec4D's Morphologia, Rawn's Mini Morphs, Trekkie's 130, I13's Real Details, Lyrra's Shape of... I don't find her all that lacking in Morphs for as little time as she has been out and am willing to be patient for more.  And because there has been more produced for her, I've found that her content prices have stayed in line with other marketplace content, so I haven't had the unending pay lots more for a lot less that all the other figures I used suffered from.  I've spent a fraction of what I did on each of the other figures I used and already have way more to work with.

 

So, for me she is a success and I hope to see her flourish.  Of course only time will tell, one can't force vendors or freebie providers to support a figure.  :)