I first read this late last year, and was slightly disappointed. I felt that it was a bit by-the-numbers, and that Donaldson was taking too much for granted in the way in which he developed both narrative and character (particularly the latter). The Covenant books are quite uniquely inwardly-focused for works of epic fantasy, and, in the past, one of their most compelling features has been the psychological leverage that this has generated in playing out the familiar inner voyage/external quest narrative-parallel, as experienced by both Covenant himself (qua 'Unbeliever') and Linden Avery. In Runes, by contrast, Linden appears as almost a fully-fledged 'power' - there isn't the sense that every step she takes is won at great personal cost, as there was in the first two series - and consequently her progression is less gripping (less compulsory, as Donaldson might have put it).
For me, Runes also lacked the sense of wonder - of discovery, and uncharted shores, and other worldliness, and all of that inexpressible stuff which is really the whole reason that I read fantasy at all - which characterises all of the previous Covenant books; nor did I feel that there was a qualitative deepening of the Land's mythology, as there had been in the Second Chronicles when compared to the First. On top of that, the book seemed a bit clumsy in its haste to reintroduce nearly all of the Land's significant groupings - the Haruchai, the Ramen, the Ranyhyn, the ur-viles, the waynhim (the giants being present on the margins but not yet having made an actual appearance and the Elohim seemingly assuming a greater significance)...
All of that said, aforementioned disappointment was probably at least partly treaceable to two, related factors. First, my expectations were very high, the book being not only new Donaldson but, even better, new Covenant (ie, a new book in my favourite genre - fantasy - written by my favourite author in that genre, returning to my favourite series in said genre...little wonder I was excited!). And, second, due to that first, I raced through the book in a couple of days, wanting to know what would happen, despite being really too tired to be absorbing it properly. And despite all of that, of course I still really, really liked Runes - how could I not?
I knew that I'd want to read it again soon, so I hung on to my copy (which I'd got from the local library) and did indeed re-read it over the past week, three weeks or so since the first encounter, which has given me a somewhat different perspective on Donaldson's return to the Land. On this pass, I read the book more carefully, and consequently better appreciated the inherent richness of Donaldson's imagination and manner of envisioning and portraying worlds and characters, and was reminded more of why I liked the Covenant series so much in the first place. I still don't think that Runes is up to the standard of the six that preceded it, but it makes more sense to me now, particularly if it proves to be a transitional work leading into a (four-part) "Last Chronicles" which eventually does prove richer and deeper than its first volume is in isolation.
Needless to say, I'm keenly awaiting the second book in these Last Chronicles, and while I've already integrated Runes into my mental Covenant/Land-scape, I wouldn't be surprised if I end up reading it a couple more times before that second instalment does come out...