So, I just finished watching season one.
Overall it's better than what I thought when I watched the first episodes BUT... although I like the style of the backgrounds and the overall "Ralph Mcquarrie" style, I still think the last seasons of Clone Wars were just more beautiful and more visualy "detailed".
The thing that also made Clone Wars more interesting was the diversity of characters and stories. You could have one episode for kids with Jar Jar but then you'll have 3 episodes about a big battle, then some "characters episodes" centered about Obi Wan or Yoda or the Force itself, etc. While in Rebels, you almost have the feeling to watch the same sort of story again and again with some twists here and there to make the story goes on.
I hope season two will bring more variety to the stories, and I don't forget that I did not like much Clone Wars when it began either. So I'll give Rebels another try.