A lot of people (especially writers) give Stephenie Meyer a hard time. And rightfully so, her books are not terribly well written and Breaking Dawn makes me want to hurl.
I do think you have to examine any extremely successful person and examine why they were able to stand out among the crowd. She DID get published. She HAS made millions. So she must have done a few things right.
Here are my guesses as to why Meyer had such success:
I think Harry Potter had a very large female reader population who was left with nothing once that series finished. All these girls/young women were looking for a nice chunky book series to fill a hole. I think Meyer was lucky enough to fill that niche.
A huge aspect of why Meyer has been so successful is that she was able to recreate what it feels like to fall in love that first time. You can argue with me all you want, but I really do think she did this well. Though, this is also what makes her writing poor because in order to capture this feeling, she did things like describe Edward's eyes 876,253 times (I made that number up, but you get the point.) All the repetitious descriptions of Edward, while poor writing, do take girls back to when they were teenagers where they would obsess over that one boy. From doodling his name over and over and over. To memorizing where he'd be at different parts of he school day. The repetition of her writing reminds us what it was like to be all-consumed by thoughts of one person.
I don't think the series would have been nearly as successful without Jacob. If the books had just been about Bella and Edward, it would have sizzled out much earlier. The smartest choice Meyer ever made was to put Edward on the backburner for book 2 and take the time to develop Jacob's character. And then, what she did was make two characters that are such polar opposites. I must say that she did a good job in making both characters so different, but still making them both lovable. Edward being uptight, cold, protective, dangerous. Jacob being a fun-loving, warm, honest, comforting. I really do think she did a good job of developing these two characters. They are the ones that drive the stories.
Soooooo... Yeah, Stephenie Meyer is no Shakespeare. Yeah, her last book is a joke and she doesn't know how to end a series. Yeah, there are better writers out there who deserve to make more money than she does. But the reading population doesn't buy books based on how well written they are. Meyer is a commercial/popular writer who found a niche, created a brand, and milked it for all its worth. She found a subject with mass appeal.
And so I think a lot of the writers who criticize her have been bitten by jealousy. But if you want to make money off your writing, it's not just how pretty your words sound, you have to consider your audience. Does this have mass appeal or is it too edgy? You have to think about it. Meyer hit on a idea with mass appeal, and then gave her audience what they wanted most.
And yes, I will admit I saw Eclipse last night. And yes, I enjoyed every minute of it. (Though that will probably be the last Twilight movie I enjoy.)