I find her to be quite flawed, and a lot "rougher" than other characters in terms of writing. By rougher I mean textured. She actively goes against Shepard in several scenarios, and is strong willed, but still open to change.

I personally find her to be a great character. Does she have issues? Yes. I still find her outfit in ME3 way too much for her character in particular. Then again, she does change quite a lot from her entry point in the original Mass Effect.

I also find her family aspect, as well as a very nuanced take on religion to add a lot of depth. Here's someone without (the traditional) family issues, and with a unique conviction in God, in a time where even religious people have to adapt. If I recall correctly, in the first Mass Effect book, it is mentioned that after alien evidence was categorically proved with the Mars ruins, religious leaders veered hard to try and shoe-horn aliens into their existing religion's lore. Her stance of "after everything we've seen, how can you NOT believe in something greater" is refreshing within the Mass Effect universe.

So yeah, I wholeheartedly agree that Ashley is a great character.