Definitely strong with map visualization. They're based on OSM map data, so weaker on anything that as to do with geocoding and routing (business data, speed data, traffic data). For good routing and search, you need to look at professional platforms from TomTom Maps, HERE, ESRI or similar.

I'm a Mapbox employee so take my note with the typical grain of salt - live & historic traffic is available via maps and APIs in these geographies, https://www.mapbox.com/api-documentation/pages/traffic-count... and you can add turn by turn navigation into your own applications with the SDKs, https://www.mapbox.com/navigation-sdk/. Let me know if we should dive deeper ;)

Main/only weak thing of Mapbox is that they are not free and unlimited for mobile apps, Google seems to remain that.

Where do you see Google is free and unlimited for mobile apps?