Jill is very quick about replying. However, you should be slow about accepting. I can say that she is essentially a competent agent with a decent record of sales, but she will want you to rewrite (dumb down) your book into something more commercial. If you just want to make a quick buck, this might not be a bad thing...but if you are attached to your vision, she may not be the right agent for you.
Also, read her contract very carefully.She does not have a standard contract. As a trained Harvard-educated lawyer, she writes her own, tailoring each for each client, ensuring she gets what she wants out of each deal. For example, she will try to commit you to giving her the right to negotiate all furture adaptations of the book (including movies) before securing a book deal with a publisher. She will demand a percentage for a successful sale whether she negotiates it or not. So, if you work with her for a time in which she yields no results or simply have a falling out, she will want to collect a hefty percentage if you decide to go with another agent who succeeds where she failed...
Most agents will engage you in a good faith effort...If the arrangement doesnt work out, you just go your separate ways. No harm, no foul..Jill wants to be paid no matter what and to commit you to giving her more business before she has proven herself.
Jill wants to make sure her interests are represented so she negotiates to ensure she gets what she wants out of the deal. When talking to her, my impression wasnt that she was looking for talent to nurture and promote, but that she considers every query an opportunity to enhance her bottom line (along the lines of --whats in it for me?)...and so she will try to tailor engagements with writers to maximize her take as opposed to advancing your vision and nurturing your talent. As long as you both are on the same page about this, this is not necessarily a bad thing.
As stated, she is a decent, competent middle tier agent...but read her contract over very carefully and make sure you are agreeable to her terms before signing. Also make sure you share her vision as she tends to recommend dumbing down manuscripts in the interests of securing a bigger advance for your book. She will also get very impatient if you chafe at her recommendations/revisions. She wants things done her way.