I actually read this book a long time ago, back when I was still in high school. I could even recall two scenes, which is a testament to how much I liked it back then. 
 Unfortunately, times change and so does taste apparently as this time around I couldn't even bring myself to finish it. The entire thing is your regular 80's fantasy with all the flaws that entails. One note characters, an antagonist that is all powerful and evil just because, the people from our world trapped in another one (which adds absolutely nothing to the story here), the free bestowing of all sorts of powers, skills, and destinies on the main characters without them doing anything for it, and finally the ham-handed integration of other existing folk tales (Arthurian in this case). 
 But the real killer is the near complete absence of character agency. While the first book still had a single noteworthy choice, this one is just everyone getting pulled along by the plot. Point in case:(view spoiler)[Kevin's sacrifice, which could have been a key point, is instead framed as something he had been destined for all along. Similarly, there's Kim who's choices are all informed either by the visions she receives or the magic ring she wears. Seriously, that ring has more agency than she does. (hide spoiler)] 
 It's odd really, since I read Sailing to Sarantium from the same author which is a far superior series in a similar style only without the terribleness I mentioned above. Such a difference a decade can make.