Before we begin, let’s be clear on one thing: Flash is not inherently evil. On the contrary, many websites owe their usability and original design to Flash. It’s only when Flash technology falls into the wrong hands that things can go badly, badly awry.
To illustrate, consider what is likely the most grievous of Flash misuses, the Flash intro. For those who don’t know, Flash intros are those full-page animations that play when you first arrive at some websites. True, the first time you saw one, you may have been mildly impressed. But if you’re like most users, the sight of a Flash intro now prompts an immediate and desperate search for the “skip to site” button. In one study, a full 80% of users demonstrated a clear distaste for sites with Flash intros. Note that “distaste” might be putting it a bit mildly considering the rants from some web users (check out the first item on one bloggers list of "13 Ways to Generate Customer Hate" or this post about Flash intros from Angry 365 Days a Year).
But a Flash intro can do more damage than simply irritating users. In some cases, it could prevent them from ever finding your site in the first place. The problem is that search engines typically consider the first page of your website to be the most important, so if this page consists entirely of a fancy flying version of your logo rather than the more substantial content of your home page, your websites rankings will suffer accordingly. Add to this the fact that any Flash content that’s not carefully created can be hard for search engines to understand and you’ll start to realize just how much of a disaster a Flash intro can be.
To be sure, there are plenty of places Flash can make your users like your site and feel good about your company. The temptation to include a Flash intro, however, is one you’d be well advised to resist.