I find this not all that hard to grow but they are categorized as such in many plant guides. One great thing about it is that it's a great indicator plant. If it's not doing well then something is off in your tank----micro or macro ferts are too low, CO2 insufficient, lighting not right.
I had it thrive for me at first a couple months ago. Then I did something stupid and instead of leaving well enough alone I listened to someone who said I was doing something wrong with my macro fert regime. So I adjusted based on their recommendations. Within two weeks almost all my plants began to suffer but the R. macrandra was perhaps first and suffered the most, with crinkled new growth, pinholed leaves, and losing it's gorgeous color. And while other plants, mostly in retrospect, were also not doing all that well, the other plants were not showing issues as much and I probably would not have noticed as soon or as obviously as I did with the R. macrandra.
I went back to my normal regime and now 2 weeks later and the newest growths are once again a rich red with yellow sunset-like highlights, the leaves are nice and robust and it's pearling like a mad dog. For the reason of being a good indicator plant alone it might be something good to try....
