In the final book of the Fionavar Tapestry, the armies of the Light and Dark meet at last in Andarian. 
 In the final book, some of the problems have been corrected. The disjointed tone of the five modern Canadians in a high fantasy setting has been done away with - all five Canadians have thoroughly adopted the local way of speaking. 
 Of course, the high fantasy lingo is its own problem. Kay's prose gets described as "poetic" and "lyrical," which basically seems to mean that Kay uses a thesaurus when a perfectly common word would have sufficed, and he mangles sentence flow. See exhibit A: "For a long time Coll of Taerlindel at the helm of his ship had fought the wind" (p.126). 
 I'm not a fan of the high fantasy lingo, but I can deal with it as long as it isn't too excessive. Kay teeters at the line. 
 My other big complaint about the book (and, really, the series in general) is that the stated scope of the story is so large - not only is the whole world at stake, but all other worlds as well! - and yet the geography is so small. Characters get from one end of a country to another in a day or two on horseback, and there are only a handful of countries to begin with (and only two that feel more substantial than a handful of hamlets, both with only one proper city each). Even so, Kay seems so disturbed by distance and travel time that he's still given half the main characters the ability to teleport. 
 The scope problem extends even further. Despite Fionavar being the template upon which all other worlds are patterned, it is incredibly European. The Cathal have an orientalism to them, but most of the mythology Kay uses has a very western/northern European flavour to it. 
 The worst part about these issues is that they could have been so easily avoided. Doing away with the "through the wardrobe" trope would have solved a lot of the tone issues. Having the world of Fionavar, and its conflicts, matter for them own sakes rather than going on about the pattern on which all other worlds are based would have solved most of the scale issues. But that would require Kay to trust in his own narrative, and to trust that his Canadian readers could care about non-Canadian characters. 
 But all of my whining has to do with the series as a whole. On its own, The Darkest Road is actually pretty okay. I enjoyed seeing how all the various plot threads resolved themselves, and there were quite a few very satisfying payoffs. Had Kay dumped the "through the wardrobe" trope and condensed the narrative into a single book, I could have overlooked many of the story's other issues.