Splash screens are those cutesy home pages with some sparkly eye-candy. After waiting and waiting a person is supposed to click on an 'Enter Here'
type link.
Flash animation may be really cool to watch the first time. If a person is forced to wait through it, every single time they go to your home page, then it becomes very annoying.
Splash screens are stoppers.
Imagine going to Wal-Mart. As you were about to open the door, out pops a 30 second (or several minute) long commercial. Would that make you want to go to Wal-Mart again or even continue to enter the store?
Approximately 25% of people never go further than a splash screen. They stop the page from loading and go someplace else. You have seconds, not minutes, to capture a reader's attention.
Good web design will have the most important information on your home page, not a long loading Flash animation.