I find flash in general is a detriment to my clients. Not everyone is web or computer savvy. When programming a site, I ponder whether or not my mom could navigate through it. If my mom were a potential client and she were prompted to download the latest version of flash player just so she could read my site I think she would run away. Click out and never come back.
Flash has its place. Strongbad would suck without it.
I really should build some flash for my site so people can see that I'm capable of it. But really, right now, I have no interest in it.