Those points aside, there are some good things I can say about it.
- While no one can surpass Scar as the ultimate badass of the lion kingdom, some creatures can rise to meet him. Kovu doesn't quite make it there, but he gets close enough. From his off color to the beard on his elbows (and later, the scar), his physical appearance is enough to evoke memories of the past tyrant, and that's really all he needs as a character. I don't think he was meant to be particularly deep or riveting; he was meant to be compared to Scar. Everyone who watched the movie made comparisons throughout, and Kovu wasn't quite adequate. This shortcoming defined his character, and its prevalence served its purpose well.
- How many supporting characters do you know who have been able to carry their own show? Not many, I presume. Timon and Pumbaa were two of those few. From the original movie into the second, they were a consistent duo from which you could always expect a good chuckle or a smirk at the least. They weren't quite as witty in the second installment, but they never seemed washed out. Even their cartoon managed to keep the flavor alive through three seasons of misadventures.