Russell Barkley has said ADHD is not a gift. He's right, however there still can be positives to ADHD.
His argument is understandable given his clearly stated motivations. His goal is to get help for people with ADHD, and pointing out the positives frustrates that goal. I think we can still work to get accommodation for the disability even while recognizing there are some positive aspects to ADHD. The first analogy that comes to mind is that we can recognize the problems that stairs and steep inclines are for people in wheelchairs while recognizing that on a gentle decline people in wheelchairs move easier than people walking.
So what are the positives? Some of the time I like the distractability. I naturally notice changes better than the average person. For example I may notice the new car in your driveway, or the rabbits eating the dandelions (or the tulips!) on your lawn. The problems with emotional regulation is the biggest negative for me, and the reason I choose to take medication.
Barkley calls ADHD a blindness to the future. I think this contributes to my natural optimism. Humans assign a greater weight on negatives than they do positives. I tend to think about now instead of the future. When picking courses in university I would pick ones I liked. Most of my fellow students would worry about their GPA, so they would narrow it down to the easy courses first, then pick the one they liked the most. When I pack for a trip I take what I need instead of packing for every possible scenario I might encounter. I have significantly less anxiety than average. By anxiety I mean fear about possible negative events in the future. I don't see as far into the future, so I don't see many possible negative events in my future.
So where does that leave the gift or curse question? Well, the question is wrong since it restricts the possibilities to a gift or a curse. In reality the possibilities are ... endless! :-)