Heck, my five year old would need help on the cheerios task!!
Your son IS old enough for simple commands, but I think you may be expecting too much of him. He DOES understand, and he DOES respond, which is more than some 2-year olds would do. But kids that age and even older, need guidance to stay on-task. Partially, they simply don't have the attention span, and are easily distracted, and partially, they want to play and make a game out of everything.
I found the worst age for this was actually around 3-4 when I had to repeat myself 100 times. Songs, like a clean-up song, help. Now at 5, threats are a little more effective too since my daughter clearly has times when she is trying to puch my buttons. However, at less than two, your son is not trying to aggrevate you. He is simply distractable and if anyting, seeking your attention.
By all means ask him to do things - kids this age love to help and do jobs around the house. But keep your expectations in check. It sounds like he is doing just great.
By the way, the worst is potty training. I actually liked diapers better, becuase I could just do it and go. Potty training means standing in the bathroom for 30 minutes saying, "Go potty, no stay on the potty, wipe, no wipe better, pull up your pants, no pull up your pants, no pull up your pants now, no don't touch anything, etc..." :)