Myanmar is insanely beautiful country. I visited it back in 2008 when military junta was still in power. I have not been to Mrauk U, but spent few days near Sittwe, and also visited Bagan, Yangon, Mandalay, and Kyaiktiyo Pagoda. Not sure about now but back then there were absolutely no ways to use the payment cards so I carried around a thick stack of dirty 1000 kyat banknotes.