Congratulations Pierre, on your first new mobile release on the IOS platform since Windows Mobile times

Even without testing the app as yet myself (I would need my friends iPad 2), the screenshots and app description look really appealing.

here are my immediate feedback points just for you, Pierre, and the forum to read:
1.) You could charge a small negligible fee for this app e.g. $0.99 USD / €0.80 EUR for a version that has all FULL features whereas a free version would be limited to certain features. You could consider this for a future version. I feel that with all your development going into XnView family you should make some financial gains which would serve to support future XnView family development but also (human nature) make some little profit for yourself too. Actually, you could charge whatever you like, I know I would if I was a dev.
2.) Consider dropping the suffix "Fx" in a far future version - at this time in future XnView Mobile would become be a viewer & browser too
3.) An Android and Iphone version (which is already planned) is eagerly awaited.
4.) Remember to take note to support up to high-resolution screens e.g. 720p HD (as seen on Galaxy Nexus >>Android 4.0 ICS). I think that you are already supporting high-resolution since iPad itself has a 1024x768 screen display.