Score Wizard 4+

Initially my only criteria was for an app that I can turn pages both by training the piece and by BT pedal as a replacement for another app that had long been unsupported. I tried a few, but score wizard ticked all the boxes, and a lot more besides...
Support for BT pedal was a given, and training just worked, but then came all the pleasant surprises:
1) Previews - when a page is 75% complete it overlays the first line of the next page!
2) straightening bent scans - scanning from music books can result in the staves being bent, especially at the edge where the bind is. Score wizard straightens all bent staves as part of the import process.
3) auto crop - when importing, score wizard will maximise the amount of screen area devoted to the music. It just works and makes playing pieces in my 10.2 screen a breeze. No longer squinting.
3) import from photos - why bother wasting time scanning, when I can now just take a picture of a page of music, and score wizard will import it, with all the corrective wizardry (pardon the pun)
4) annotation - anything can be overlayed on the music and in a multitude of colours. Commentary or reminders to play in a certain way are easy to add.
Musicians who need/want to digitise their collection, and to benefit from all the aids that technology brings, need look no further than score wizard. It does everything it is designed to do, and does it very well indeed. Highly recommended.

I have been using Scorewizard for a while now and I can confirm that it is very good indeed. It is an excellent viewer (especially now that it also has sepia mode to reduce the white glare). The import function works very well where it will automatically straighten curved scans, crop them and make them look like a sheet of music. It has a feature where you can train it to turn the pages automatically. You can also turn the pages in the usual way by swiping with your finger or using a wireless pedal. It also has all the usual annotation features that you expect from a pdf reading app and a facility to quickly flick through thumbnails of the various pages in the file.