I havent tried them but what i have discovered about hookah stuff and pretty much anything else you buy for that matter is you get what you pay for.
the last couple weeks i decided to try different coals from my usual coconaras. i bought AF natural coals and jap style coals cause you get a ton for way less than coconaras but i found to dislike both of them greatly. the AF burn too hot and the jap coals dont burn hot enough and they both ash like crazy and are hard for me to manage.
I know the cheap price and the large amount of coals you get makes it tempting but from my experience with coals i would stay stick with what you love even if it is a little more expensive =)
Here is a youtube review of Nakhla coals
Hope this helps