Bug description from our customer:

"Hello,

we use the OSM plugin in our android and ios apps and it seems that the android osm map looks sharp but the ios osm map looks blurred.

We tested on Android:

• Nexus 7
• Samsung Galaxy S3
  ...

And on iOS:

• iPhone 5C
• iPhone 5
  "

I've tested this on iPad retina and also on different 'emulated idevices' (iOS simulator). The problem is visible on 'retina' devices and seems to be dpi-related.
Making tiles sizes smaller (QGeoTiledMappingManagerEngineOsm, 128x128) and setting device pixel ratio as 2 in QGeoTileCache::get kind of fixes the problem (but not a fix obviously), but suffers from another one (probably, expected?): text labels on the map are very tiny and hard to read. I'm also attaching screenshots.