“Flash is a great way to enhance a website”. I think the operative word in that sentence is the word enhance. Flash can lend itself really well to add those dynamic touches to a website and if used well and make a real difference between a boring site and an exciting one. Take http://chic.edu/ for example. Flash is used conservatively at the top of the page and this adds a real sense of sophistication to the whole page. However, if overused, this can lead to a potential Death by Flash.
Personally I don’t mind a bit of gloss as part of a website, however the thing that really annoys me are complete sites built in Flash. It’s not just because of the fact that they are harder to navigate (as each site designer can implement his own navigation style), but also because the whole website is one atomic package. There is no way to address content buried in the site, there is no way to interact with the site programmatically, there is no way to even access the site unless you are using the right technology. And this to me is very anti-Web. I suppose I’m singling Flash out here because of it’s prevalence, but the same idea applies to Java websites, ActiveX web-controls, Silverlight and all the other technologies which trade away usability for the sake of standing out from the crowd.