To paraphrase Rob Pincus, in a critical situation, the adrinline rush can cause limited fine motor skills, resulting in fumbling. He advocates a manual release of a locked back slide as it requires less fine motor skills. Secondly, I generally cannot reach the slide release button on most pistols without altering my shooting grip on the pistol. So I don't use it.
No offense, but I've been training on combat handguns since I was 8 years old. Personally, I don't think it's all that difficult a consept, but I understand if you might have issues with it due to lack of familuarity with shooting.