While this is what you'd expect from Ovi, it doesn't work that way. You can sync your data with the Ovi server only with a limited number of devices, but you can't get it out again (like sync it with your desktop mail client or another mobile device) except you use a special Windows-software. So as the typical consumer (1 phone and Windows) you do need extra software to sync. Other users (phone, tablet, GNU/Linux) cannot sync at all.

This basically limits the use of Ovi to an online backup - if you get it to work at all. My phone for example should be supported but fails to sync ("server error"). Nokia support is unable to help me, other users of the same phone report the same issue.

OTA firmware updates are much the same: They might work if you're lucky, but there's the same chance that they don't: OTA will tell you there's no update available when in fact there is one. You'll still need the windows-software for reliable operation.