I only have an original Droid and I quite like the option, I like to stream sports when I can, as well as episodes on places like South Park's site.
I have it on demand, so basically it's off until I click it active (much like flash block), so it's a non factor until I need it to be.
Phones are getting more and more powerful. We're shipping with a gig of ram and dual core phones. They are plenty powerful for Flash. New chipsets and graphics will be flash accelerated.
It's not something you use all the time, but it does make browsing a more complete experience over the iPhone in my books.