It's often seemed to take me awhile to fully appreciate the subtleties of particular drugs.
Methamphetamine was my DOC for years, but the first time I tried it I was less than impressed. My previous experiences were with mdma and ketamine, so I was used to a very different, intense, dramatic high than the more exaggeration of natural feelings that is meth. I guess the functional-ness of it took me by surprise, I was expecting to be more impaired, so I underestimated its power.
Opioids were similar, it took me a long time to appreciate that high, because of the same reasons. They were an acquired taste for me, it was a long time before I appreciated all their intricacies, which can be easy to miss when you're not familiar with the high. I agree with the other poster who mentioned how easily the high can be interrupted - I was more familiar with all encompassing, 'fucked up' highs when I first tried opioids, and again, the subtleties meant I underestimated them at first.