I think Darius_Sedai and DomA did a great job highlighting the most frequent critiques delivered against the series. I just wanted to follow up and say that ultimately, I think it has less to do with him being a bad writer, and more to do with the sheer fact that certain themes and details didn't clarify themselves until well after the series progressed - unlike most authors and series with limited installments (one, two or three book trilogies, for example), "The Wheel of Time" was released in such a way that there was no opportunity to go back and re-do or touch up prior scenes before they became part of the final version. For example, I read "The Shadow Rising" well before I read "The Eye of the World", and to me, there is a huge difference in quality of writing and originality; the latter felt like a derivative piece of fanfiction, while the former is easily one of my favorite books in the series and alternative fiction, in general.

This series to me feels as if it had been born from great ideas, but ultimately the weight of all the characters and story lines drag it down from being as well-executed as it could be. For me, the key word is execution. It's a great series, but for one this large, an editorial and creative team might have been needed to keep the universe coherent and tightly woven.

That doesn't make Robert Jordan a bad writer; it makes him an ambitious writer. I don't think he was entirely successful in delivering the potential the early part of the series held, but neither do I think he was a failure - I think most fans have lists of books, characters and storylines in the series that were boring, lacking in believability or just plain sloppy, so it's not really possible to claim he succeeded on all fronts.