The one thing I didn't find a solution for, was the hundreds of notes, I'd been writing on Symbian phones up through time. Foolishly of me, I never switched to Evernote/OneNote while on Symbian.
And the Transfer my Data app on WP doesn't help you with notes from the built-in Notes app.
But now that Microsoft are terminating Nokia Sync, there actually is a solution.
Simply check the checkbox for migrating Notes, and they will migrate it to OneNote for you.
One thing, I experienced however, is, that with the hundreds of notes, I had, the migration tool couldn't handle all of them in one migration. I had to close the browser tab and restart the migration three times. Each time you can see, that it has migrated more notes, and the third time it migrated the last of them.
The migration option closes on 5'th of December, so you have to move fast :)
Thanks Martin. OneNote may not sound that exciting, but it's available for all major platforms, so at least gives your Symbian Notes a future.