It's the only prequel I would be interested in. And I think it's easier to finish than 'Winds of Winter' and 'A Dream of Spring' because it's only centered around 2 persons. It's a bit like the travel with Arya and The Hound meeting interesting people and having lots of adventures. Since they go all around Westeros they could link it to The Starks, Lannisters, Freys, ... All the families we already know and some of them were still alive at the beginning of 'A Game of Thrones'.
It's a pity because if we have to wait until he has finished 'Winds of Winter' and 'A Dream of Spring', we can wait forever...

I really didn't like the characters in 'The Princess and the Queen' and 'The Rogue Prince'. If they would chose those, I hope they make them more interesting.