Most of us really like the look & feel that Flash can add to your web site. There are a couple of downfalls to it, though. The question of whether or not to use it on your site really depends on what you want your web site to convey.
Flash looks great on a web site. The site itself can be more clean & crisp if built entirely with Flash. You can use animation on your site to keep the visitor's attention. If having a highly polished site is your most important goal, then you may want to consider using Flash on your site.
The first thing that I think of when I think of Flash is that it's a search engine killer. Google is currently the only search engine that can recognize Flash while indexing your web site. This is bad news for businesses that rely on high search engine rankings to reach customers. If you need high search engine rankings, then Flash should not be used on your site for more than the splash page -- and possibly an element here or there (but not when it's using keywords). If Flash is used throughout your site, it will bury your site in the search engine rankings.
Flash can be expensive. Flash is an elaborate program, so it takes a lot longer to design a web site using Flash. Because of this, the costs can pile up fast. Most businesses have a limited budget for their web site, and this drives them away from using Flash.
Finally, one of the pros can also be a con. Some people are enthralled with the animation that can be provided by Flash. Others, however, find it distracting. A key thing to keep in mind is to not overdo the animation. If you have more than 1 animation at a time on a page, the visitor will be too distracted.
For most businesses, we'd recommend not using Flash for anything more than the splash page. If the search engines can start indexing Flash more proficiently, then our feeling would change on this. The pros don't even come close to outweighing the cons right now. It can be costly, and also buries your web site in the search engine results.
However, if you are not trying to attract customers to your site through the search engines, then it would be worth considering. Just make sure you have a nice budget to build your site.
Scorching Web Design