Nokia N900 is equipped with FREE maps 1 navigation software. It has a good performance compared to other free apps. - good maps (which you can download in advance) satellite view, 3D view, international routing.
It has NO voice-guided turn-to-turn guidance and No recalculation. But I didn't so much of that in maep or google maps either.

I did have the same basic possibilities on my N95 with Maps 3. On that device, i bought voice guidance and recalculation for a yearly fee.
So, what's the difference ? You can't compare a free service with a service you have to pay for.
For me. ovi maps 1 is competative with maep and other free services, and ovi maps 3 is quite a different thing.

I hope Nokia comes soon with maps 3 and the paid for services.
Otherwise I will by the same functionality from sygic.com. It seems that bad weather is ending soon at Sygic.