It's not a high. If you're getting high off of ADHD meds you either don't have ADHD or your dose is way too much. It's more like an assist for task initiation and follow through, as well giving a boost to staying on task, for people who find those things incredibly difficult _even if they want to do those things_.
No, speaking personally I don't consciously notice the effects of Concerta. Far from being a high that I crave, I actually have to set myself reminders in the morning and make a ritual/checklist, and I set my medication out on a visible shelf in the bathroom, otherwise I'll forget to take it.
I'm not sure how many people with addictions are regularly forgetting to take their drugs without a phone reminder.
The point of the delay release is that you don't have the same kind of ramp up to extreme effects and then come-down. Instead the goal is to get a (roughly) consistent dose that helps with executive dysfunction, and doesn't do much else. As always, that's something you work out with the help of a psychiatrist, not everyone reacts to methylphenidate the same way.
