Yes, I've had some personal experience and it wasn't encouraging.
She asked for my manuscript and after it sat with her for 3 months, I emailed a polite inquiry about status. Nothing.
When she ubdated her listing, the email had changed, so I emailed again. Still nothing.
Finally, after 5 months, I wrote and asked her to withdraw my MS from consideration (another agent wanted it as an exclusive.) Guess what? Instant reply for Moreen.
She claimed she never got my emails, had started/stopped reading my MS, was overwhelmed by submissions, it wasn't her fault, yada yada. She was very nice, but, I don't think she was being completely honest.
She also basically said it was no skin off my nose since there was no expense involved on my part. She forgot that she had asked for BOTH hard copy and an emailed copy of my manuscript.
She doesn't ask for an exclusive, so I suppose no harm. But what happens if you sign with her? I don't believe the experience will be a good one. I believe your MS will sit in limbo for at least a year and never sell to anyone.
By the way, my MS has already been optioned for film rights. There is a screen play written based on a much earlier/different version of it. It was shopped by the screenwriter's very good agent, but like most options, wasn't picked up. Getting an option and some money out of it wasn't that hard. But it's like being engaged to be engaged; no guarantees on the next step.