It's a great outcome, and a huge win for science.
Science is about discovery. And now that we have an actual definition of what a planet is, we can go on discovering and classifying celestial bodies that are out there, both in our solar system, and others.
Remember, Pluto was only discovered in 1930, and at that time we thought it was much larger than it really is. In science we learn more about something, and we re-classify it if we need to. For example, we ourselves are all animals, it cannot be denied.
There is so much we do not know about our solar system, and projects such as the hubble space telescope have allowed us to learn so much more about our solar system, and the universe at large. There is still alot to learn out there for a long time yet. 8)