First ever cartoon huh? Welcome to animation. Right then, review.
Pros: Humor was pretty good. Not the overly derp kind of humor I see sometimes (and dislike), I liked it. Nice to see you know mega man, using Magnet man as a proper cameo (be surprised how many wouldn't see why, say, Shademan isn't supposed to be active at the same time as Shadowman).
Cons: Art could use a significant amount of polishing. Voice acting could stand to be improved (Roll sounded like was recorded somewhere with an echo for example, was also difficult to understand Wily at times).
Other: I won't say this was among the best I've seen, but given it's your first cartoon, I AM fairly impressed. Keep at it. You'll get better with practice. Some of my favorite megaman toons here has subpar art style, so it's the overall result that matters. Nice job.