My personal opinion of flash:
At one point in time (before i jumped into the Linux world) I was a flash master, you could ask me just about anything refering to Flash 5 and I probably still know the answer. And if used correctly, flash is great. But, and here's the big part, the but, if used incorrectly it is extremely annoying / agravating / stupid / <insert insult here>. For a site that is really mean to server content and or information, flash is not the answer, also, it is slow for dynamic data (although apparently this improved with flash MX (6) ). On the other hand, if you want to make a site that is kinda fun, and more entertainment oriented, if implemented correctly, including a HTML only version available, flash can be great.
Unfortunately, it seems that at the current time, flash is used more for evil than good, and often poorly implemented. Due to this it is being hated by more and more people, and with good reason. If all of the web developers out there had the right idea about what flash should and shouldn't be used for, i belive that the technology could be great, but it is evident that a LARGE number of flash developers just don't get it, so it's facing more and more hatred.