When we have clients who are thinking about Flash splash pages, we tell them to go to their local supermarket and bring a mime with them. Have the mime stand in front of the supermarket, and, as each customer tries to enter, do a little show that lasts two minutes, welcoming them to the supermarket and trying to explain the bread is on aisle six and milk is on sale today. Then stand back and count how many people watch the mime, how many people get past the mime as quickly as possible, and how many people punch the mime out. That should give you a good idea as to how well their splash page will be received.