A lot of words are flying back and forth about using flash on the iPhone and soon to be released iPad. I've found this video to be very interesting in explaining a lot of the points.
They are mainly talking about flash as a content provider and not a the main UI but some of the points are relevant and they explain what you are really getting with Flash lite.
Here i the orginal link where I got this from http://www.appleinsider.com/articles/10/02/20/inside_apples_ipad_adobe_flash.html
Jason