Another "from Incredible to Galaxy Nexus" person here. I do wonder how the OP has a 2+ year old Dinc when it released on April 29th of last year...
Anyhoo, here's my thoughts so far:
Form factor:
The Nexus seems HUGE sitting next to my Incredible. Both phones are thin and light. The Incredible is great for one-handed fast use, but suffers from the need for more precise input when a lot is crammed onto the smaller screen. The Nexus takes a small bit of getting used to, but its well worth the extra space. I haven't miss-clicked a link, keyboard button, or checkbox yet on the Nexus. The plastic on the Nexus seems more scratch resistant than the soft-touch and glossy black used on the Incredible. I could go on, but in my mind there's no need.
Winner - Galaxy Nexus
Screen:
Incredible - 3.7" AMOLED 480x800 pentile matrix - was great for it's time, and still looks beautify today. With the advancements of screen tech, it does show it's age though.
Nexus - 4.65" Super AMOLED 720p pentile matrix - blows away the Incredible. Colors are richer, wayyy better in direct sunlight, details are clearer, and the pentile is not noticeable. Whites are slightly less white than on the Incredible, but it's only noticeable side by side. All the pros outweigh this.
Winner - Galaxy Nexus
Battery:
It's hard to definitively judge this, especially since the Nexus is young. At first, my Incredible had not so incredible battery life. Ever since I got into modding and flashed CyanogenMod, there was a huge increase in battery performance. I could go 8 hours with moderate usage and be at 35% by bed time. Not too shabby. On the Nexus, since I have only had it less than a week now, I can only say what I have experienced so far. In about 8 hours of light usage, I've been around 70% by days end. I've been busy and not had a lot of time to use my Nexus during the day much recently, so I can't come up with a real comparison yet.
Winner - No clue yet
Speaker:
The Incredible is definitely louder than the Nexus out of the box. Like most, I have been using the Volume + app to compensate. With the app installed they are about the same loudness. What I've noticed with the Nexus is that volumes are inconsistent. The ringer is decently loud stock, but watching videos or playing music is much quieter. I'm thinking the Nexus could use some sort of software tweaking here, maybe some kinda of audio normalizing.
Winner - Incredible... for now
Camera:
I've taken many beautiful pics with my Incredible of scenic places, it had a great camera and still does. It was way ahead of it's time for a phone camera when it came out. I haven't had the chance to really experiment with the Nexus's Camera much. Mostly just messed around with the cool effects so far. Low light isn't great it would seem, nor was it on the Incredible. Daylight shots seem good. I'll have to mess with this more when the opportunity to take great pics arises.
Winner - More info needed
Performance:
The awesome performance of the Incredible is probably the main reason I was able to wait around for a phone like the Nexus to come. With CM installed, the phone runs amazing compared to some newer phones. It will still run almost any app available to it off the market and the lag is few and far between. With that said, the Nexus blows it out of the water. Literally no lag for me since I got it. Things that would make the Incredible bog down a little, like some intense live wall papers, this phone eats for breakfast. Dual core, dedicated GPU, Hardware acceleration? Yes please.
Winner - Galaxy Nexus
Sexy factor:
Fully black front with no carrier branding, curved screen, thin, minimalistic. Sorry, Incredible, Verizon's makeup job doesn't do it for me.
Winner - Galaxy Nexus
Dev Support/hackablity:
No contest
No regrets upgrading to this phone, it's a worthy replacement of my trusty Incredible.