Don't ever, ever make a fully Flash-driven website. Please.
I've recently been looking at the Singtel website to help Denise choose a new phone. But I'd like to share some opinions about the consequences of using Flash:
1) Websites that have a loading bar are incredibly irritating. This is an all-too-common feature of websites that are completely built on Flash. Don't let this happen, I would rather have a less pretty website that loaded at the same speed as any other site. Avoid.
2) Make sure that I can open new items in new tabs. If I am choosing from a range of phones I want to be able to have them all open at once so I don't have to keep going back to the list of search results to look at a different phone. The otherwise excellent thetrainline.com website is another example of this - it can only handle one journey being viewed at a time. Not helpful.
3) Flash crashes. I don't want to have to reopen Chrome every time the Flash plugin that is integral to the website's functionality crashes - I like to look at other websites at the same time and don't want to reopen them. I will make an exception for Youtube, as their video player is great. But then again Youtube rarely crashes my plugin.
So there you go, three important considerations the next time you consider building a website out of Flash. Don't. Try HTML 5.0.