I've seen many users creating really nice Flash websites. This is not a bad idea, especially if you work with Flash or you somehow have many animations/videos to present to your users in a seamless manner. However, for a regular website, such as a Snap! website, it has one major drawback: it is not SEO friendly.
Flash animations are binary files (.swf) and as such they often do not contain any readable text. Actually, if you want to make sure that the font works right, you will be using an internal font and that may prevent any readable text from appearing in the file (properly optimized text does not use standard encoding for strings of character such as ASCII or Unicode.) In any event, if the search engines do not have the necessary tools to read Flash animations and find your text, it simply won't be indexed.
Adobe offers some tools to work on those files, but it is not widely used.