Nobody here, or on any other forum really, can answer this question properly, as the EVO is not in any (or many) consumers' hands. All we can go off of is information released by tech sites, Sprint, HTC, etc. If you want real comparisons, you'll have to wait until more reviews are out and/or the phone is released.
That said, here are my thoughts on the subject.
I debated trading in my Incredible for the EVO, but it came down to this. I love the Incredible. There is nothing the EVO can do, other than 4G, that the Incredible can't that I actually care about.
720p video? In all my years of having video on my cellphone, I might've used it three times. Plus, Engadget says the "720p" is being generous in terms of actual quality.
Front facing camera? I admit this is a great feature, but I don't see it really being used in the near future. Everyone I know has video chatting capabilities on their laptops. Those I know that actually use it, myself included, use it on a very rare occasion. It has not caught on enough yet to make it useful, especially on cellphones.
4G? This is what almost got me to give it a shot. I live in Seattle where there is supposedly good coverage and 4G. Reading reviews, however, makes it sound like the 4G really only works on the streets (i.e. inside a building and goodbye 4G). Add to that that it will eat battery, and I can hold off for what Verizon has in store next. My 3G flies.
Other reasons I kept the Incredible:
Battery life on my Incredible is excellent. Others have had complaints, and I also didn't want to risk giving up my Incredible only to get an EVO that has awful battery life. Given its screen size, 4G, and other features, I can't imagine it'd last as long as my Incredible battery does (30-36 hours lately).
The Incredible is almost too big for my pocket and holding to my ear for extended periods of time, I worried the EVO would flat out be too big.
Incredible has better screen (except in sunlight).
Incredible has the optical trackpad which I find very useful when typing messages, emails, etc.
Verizon is just so much better than Sprint.
When it came down to it, there was nothing I could use to justify giving up Verizon's network, which is far superior to Sprint's. Plus, I pay $64/mo on Verizon and Sprint would've been $80, making it harder to justify.