We tried it last May for my DD's birthday (she's 4). Just so you know, children have to be at least 4 and potty trained to attend so your 3 year old might not be able to attend.
I think it is a great value compared to some other experiences, the room was decorated so cute and all of the girls were dressed up. Unfortunately our DD FREAKED out when the Mad Hatter joined the party. He is very loud and she was so scared they called me within 10 minutes to come pick her up. She had never been afraid of characters before but IMHO he was a bit overwhelming.
Thankfully the staff was so nice and actually refunded my money which was very fair. I just felt bad that DD was so upset.
Most of the girls were 6-8 years so maybe we would try again but right now DD said she would never go again. One of the staff told me that the Mad Hatter scares a lot of kids and it happens frequently.
All in all I would still recommend it as a very special experience for girls - they have a tea party decorate cookies, play games and have a parade in the GF lobby.