What's the issue with Seaver?

So I've seen a few comments in regards to Ashley Seaver and most of them weren't positive.

Watching from the first episode she showed up to the current episode 15, she's a great character with a twist to her background that makes her ideal as an agent. She relates well to victims and her personality is interesting to watch. I didn't see her as a replacement to JJ, more like an added agent they needed until she gets back.

Can anyone tell me why you do or don't like her?