Well.. lol if I was building a site I would not use flash, but that is not to say you cannot get a flash site to rank. A lot of times using flash you can really make your site awesome and the user experience even better which I feel is a metric Google looks at. So if your site has an avg of 10minutes plus onsite time, then google knows this and we usually give you a hi 5 for that lol.
There are also a lot of little tags and what not you can add to help with the onsite seo of flash sites.
There are reasons to have an not to have, but I wont build any flash sites anymore. Most cool flash sites out there are huge brand name sites anyway and they just get ranked because a bazillion people "yes its a real #" are linking to them ;-)