https://itunes.apple.com/jp/app/monster-hunter-portable-2nd/id639457826?mt=8&ign-mpt=uo=4
(Japan only for now)
1600 yen.
Supports Game Center, iOS controllers and has upgraded graphics, target camera from MH3G as well as online multiplayer.
Screenshots here:
http://dengekionline.com/elem/000/000/847/847008/
http://app.famitsu.com/20140508_369758/
Trailer:
http://youtu.be/8EAuXNxKUKk
Gameplay:
http://youtu.be/udyhAxPvT5I
Comparison:
PSP
iOS: