Prydain is indeed great, though I don't much care for Taran Wanderer. I might like it more now, but I've not read the series since high school.

It was somewhat confusing - and likely why I didn't like Kestrel as much, since Beggar Queen makes Theo's Kestrel phase seem super awesome, but it's just kinda blah in the book itself. Which I get why, but Theo is so terrifyingly awesome as Kestrel in Beggar Queen, giddy about killing a cannon, that I was hoping for more of that when I finally got to Kestrel.