Guy Gavriel Kay is (or was, I don't read much anymore except for studies) one of my favourite fantasy authors. I'm not as sure you can see the Tolkien influences (although you can read in reviews everywhere that points them out, I prefer to make an opinion of my own, and in my case I don't see much, he has enough to stand on his own), but since the story is an alternative version of the Arthur legend that's where I see similarites. Except for the Fionavar I particularly like Tigana and The Lions of Al-Rassan.
The following is just my perspective, of course; you or anyone else is more than welcome to disagree.
I haven't actually read any reviews of Kay's stuff, and I didn't know anything about his background until I was halfway through The Summer Tree, but by then I had already formed my opinion. Certain similiarities with Tolkien leaped out at me immediately – Rakoth as a variation on Morgoth, is just one example.
In Fionavar, at least, Kay does a lot of world building like many other fantasy authors, but it's his choice of words when he delivers the backstory which to me is very reminiscent of Tolkien. As well, the heroes and villains native to Fionavar tend to display the same sort of larger-than-life characteristics that Tolkien’s characters often show. Kay also tends to use more elaborate language when portraying scenes of epic battles and similar external confrontations.
But what I really like about Kay’s writing is that he also mixes his style up. In contrast to the Tolkien-esque elements, he also at times switches to a very direct, almost “old school” style of writing that reminds me of, say, Roger Zelazny or Philip Jose Farmer. Actions tend to be short and to the point. Descriptions of things extraneous to the immediate scene are minimal. Dialogue is direct, and word choice / sentence structure tend to be simpler. He resorts to this other style particularly when he’s delving into the internal conflicts of his characters, especially those from Earth. With this approach, Kay makes it very easy to relate to his characters as people as well as heroes.
I think what it boils down to is that Kay takes certain essentials of Tolkien’s style – mainly the things that a lot of fantasy fans would think of as “epic” – but he avoids the pitfall of becoming too enraptured with his own creation. He combines the best elements of Tolkien with an experienced writer’s sense of pacing and what makes for good drama – in short, I think he improves on Tolkien’s writing style considerably, adding a “modern” edge to it.
