I can speak to a few of your concerns:
1. Don't bother trying to use the Pre for turn-by-turn. I found Navit to be a barely functional eye-sore, and I was never able to get it to work properly. If you really want the Pre3 (and who could blame you?) you'll also want to factor in an extra $100-$200 for a stand-alone GPS, or I guess you could pay the monthly fee for VZ Navigator.
2. I'm afraid I don't use Spotify, so I don't have any experience with the app.
3. Evernote never gave me problems, but I'm not a heavy user of the service, and the app *is* long in the tooth and unsupported.
4. Battery life is not great, but manageable. I get about half a day out of a full charge. Put touchstones everywhere, make sure you have a car charger, and you'll be fine.
5. Apps that haven't been updated for the larger screen have a single black bar at the bottom. If you have even one notification in the dashboard, this bar gets covered up. If you really hate it, most apps can be fixed by adding a single line of code. Search the forums to find it. Honestly, the bar isn't terrible, though.
6. As I'm on AT&T, I'm afraid I can't help you there.
To sum up:
I love my Pre3, and I use it everyday to check twitter and these forums. But my sim is in my old iPhone 4. :-/
I've had some intermittent issues syncing my google calendars and contacts. I rely on the convenience of having GPS on my phone. To top it off, most of my family members are on iPhones, and iMessage is a lot cheaper than paying for a large texting plan.
Despite the fact that I'm not using it as my daily driver, I do love the phone, and I would strongly recommend it, minus the caveats I've mentioned. It's unsupported hardware, will not get system updates, and apps are scarce, but if you're going into it with your eyes open, it could still work for you.
Keep in mind, though, what $200 can get you right now if you get a new phone on contract...