It really is that good. I went from iPhone 3g -> 3gs -> Sprint Hero ->Motorola Droid -> Droid Eris.
A couple of things that I liked about the Eris over the Hero are the network, proximity sensor, and the 18 bit display. It's not as nice the Motorola Droid, but it's still very nice.
I don't think Android will support higher than 65k colors until 2.0, but no biggie. I probably won't notice a huge difference in all honesty.
Droid's display was gorgeous and some of the improvements were much welcomed, but overall it felt bland. I ran Panda Home, Open Home, and dxtop for home replacements and wasn't extremely impressed. They were better than stock home, but in all honesty I didn't like them as much as I like Sense. Sense is more than just a pretty UI, I like the people app and how it ties everything together.
All-in-all I'm happy with the phone and knew what to expect having used the Sprint Hero.