Although they look very cool, they are hard to make and edit. I found a really nice flash template I liked, but it was so confusing that I didn't know how to edit it. :\
well, thats the hard part- learning it once you got that out the way, the rest is all about your imagination
Good, if it fits your website and is loading fine for everyone else's computer. As for being 'hard', if you don't know flash then you shouldn't be attempting to use a flash template. As long as you have the skills needed, it won't be a problem. You can't go around downloading nice flash templates though and expecting them to just instantly work how you want it to. I don't know much about it, but I know it does take a fair bit of practice to learn properly. Stick to what you know if you're making a site. On the other hand, in general, if you're not the one maintaining the site, flash sites are really nice...