This is a pretty good series, although it is slow at times. I love how he puts in characters that are based on real people in history. The characters are well written. The siblings relationship is realistic.
The written is good but a different style from what I'm used too, which can drag a little. The author is Irish and I read plenty of international authors, so it's not that but his own writing style. The way is set up with all the characters being based on real people is a unique idea and I haven't read anything like it before.
The plot is good. It has the same basic good vs evil magic theme to it.