I can't promise you that Maggette will be better than Ron. However, you have to look at Ron Artest and think about your future, which is why the Kings are looking to trade him.
He's actually a pretty good player. He is a very strong 6'6'' Guard\Forward that can rebound with the bigs, but can also guard the perimeter like a guard. He's a very good scorer that can slash and create mid-range shots. He is slightly less then Ron Artest when it comes to defense, but he is a better rebounder and maybe even a better scorer. His biggest problem is his consistency and his defensive lapses he has from time to time. If you got him for Ron Artest, I would think you got a pretty good bargain.
I think he is a solid player, not one of the best in the league, but solid.
As you can see he averages almost 15 points and over 5 rebounds, he's also a okay defender.
He had some pretty good years averaging over 20 points.
This year isn't his best year, but I think he is a good player.