I truly enjoyed methylone while I had it.
I find it to be less euphoric and intense than true MDMA, yes, but I loved that it was mixable with other drugs (weed, alcohol, mephedrone, 4-fa) and I personally experienced no come down from it. I also slept quite well afterwards.
To answer your question, crystals/powder etc. are no indication of quality. Some people believe the chunkier and darker a compound, the more "pure" it is, but this is simply untrue. I have had stark white velvety powder that was intensely strong and fabulous, and I've had dark brown sugary shards that were quite lame in effects. I would reagent your stuff to confirm it's contents, and start with a reasonable dose from there.