I have read quite a few Mercedes Lackey books, but only one other Andre Norton book, so I thought of these books in comparison to other Mercedes Lackey books, rather than in comparison to other Andre Norton books.
Among the Mercedes Lackey books I've read, I liked the Last Herald Mage, the Collegium Chronicles, the Heralds of Valdemar, the Mage Storms, and Bedlam Bard. I did not like the Halfblood Chronicles and the Mage Wars as much.
I think my main complaint about the Halfblood Chronicles was that the characters were not strongly drawn. Sure they each had a different name and a different history, but they did not all have different personalities. Too often as I was reading and a name was mentioned, I would wonder, "Which one was that again?" The reason for that was not because there were too many characters, or because there were many minor characters, but because the primary characters just did not have sufficiently distinctive personalities.
I also felt the books were not well edited. There were typos, and there were some minor inconsistencies, or things that just didn't quite add up.
Also, I was annoyed that while both Alara and Valyn know something of Shana's parents, they do not share it with her. She has to live without knowing who her parents were, even though there are people close to her who have that knowledge.
On the other hand, the books did successfully hold my attention, and they offered an interesting commentary on how people are corrupted by both power and by powerlessness. It was interesting to see, especially in Elvenbane, how the oppressed can become focused on seeking the approval of the oppressor, rather than on questioning the system which they were born into. In systems of power inequality, those on the bottom may just want to get to the top, so they can oppress others instead of being oppressed.