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.
I visited Mrauk U back in 2015 and had to withdraw enough kyat to sustain me for the few days I was there since there was no ATM in the town.
The boat ride from Sittwe up the Kaladan River was actually one of my favorite parts of the trip with its peacefulness. It was just me and one other traveler on the boat.
I too visited in 2008. It really is one of the world's most spectacular countries. So much history and culture. Bagan at sunset is absolutely breathtaking.