I used to watch this show everyday after school when I was a little kid back at the early 2000s and I loved it as much as anyone else. The animation is beautiful, the characters are likable especially Timmy and his godparents, Cosmo and Wanda. The humor is witty and funny at the same time and the story lines for the first few seasons are creative. Even the voice acting for the characters is pretty solid and entertained me throughout the show.
Why did I give this an 8/10? Well, let's just say that the show later went downhill where the new episodes are mediocre and the humor isn't as hilarious as I remembered it to be. What I really hated the most is the character Poof, the baby of Cosmo and Wanda because she was the most uninteresting character and the show would've ended without her. But nope, the writers decided to give up and wrote more of the same instead of something new and original.
Overall, the new seasons that started from 2008 has destroyed a once great show. I understand lots of people hated this show, but I think that it's a good one at that. My advice: Watch the first six seasons instead of the new ones because they sucked and ruined a once great show.