Recently, I was doing a website competitive analysis for a new client. During my research, I came upon a site where the developer was clearly very successful in selling his client on the "More is Better" model. I mean this site opened with a Flash intro and Jazz music blaring and too-clever-by-half navigation—and I couldn't get out of there fast enough! Really, the only thing I hate on websites more than suddenly blaring music is a Flash intro that loads about as fast as sludge flowing uphill.
Don’t get me wrong, there are some great uses for Flash—where would gaming, video, and other high media content sites be without it. But for your average business site? Not usually. Too often, designers use splash pages to impress their clients with eye-candy. And, too often, those clients don’t know about site loading times, usability, SEO, or mobile touch screen issues ("iPad" anyone?) to know that generally this is a bad idea.
Rather than “out” the local business website that triggered this post, let me just use Nike as an example. In this case, the Flash loads relatively quickly, and is done very well, but it makes navigation really cumbersome. Give the site a whirl and see how long it takes you to X out. If there are other things you want to get done today, my money's on less than a minute.
From the user's standpoint, here's the problem with Flash intros or any non-text landing page: When people come to your website, they're looking for actual information, and because they're busy, they want instant access to your content. Instead, they find a slow loading, fancy Flash intro with flying text and perhaps booming bass blaring. (Interesting how many Splash pages also play music.) In the midst of this assault to their senses, they have to figure out where the "Skip Intro" link is. I can assure you that unless you're offering a one-of-a-kind, can't-get-it-anywhere-else item or information, you've just lost a potential customer.
Overly used or inappropriate Flash pages aren't just a buzz kill for your visitors; Google hates them too. Here's what comes up in a Google Search for another local agency (with a web department that should know better) with a Flash intro that Google attempted to index.

I've altered the URL and description to protect the guilty, but the point is that since there is no content to index on the home page, Google grabs the Flash loader. Not good.
I'm not saying never use Flash; just think three times before you do. If you care about your visitors, and about SEO—and you should, unless you don't want search engines finding your site—forego the Flash and Splash and Music, and the rest of the whiz-bang stuff. Instead, focus on useful content and keywords, and Google will reward you with appropriate organic searches that will successfully drive visitors to your site. After all, isn't that the reason you've invested in having a presence on the web?