I devoured the Belgariad as it came out when I was a teenager in the early eighties. Similarly, I thought the Malloreon was a continuation of that story, but it was stale. I loved the first bit of Elenium, but then I realized, hey, isn't that guy exactly the same as so-and-so from The Belgariad? I thought Sparhawk was a great character that was wasted in that series.
I quit halfway through the first book of the Tamuli. I read The Redemption of Althalus as a test, to see if Eddings had changed, and unfortunately, he had written the same book again. I have not read any of the extras, like Belgarath or Polgara, because I knew it would only take away from my enjoyment of The Belgariad, of which I have very fond memories.
Needless to say, I won't read another Eddings book, but I will read The Belgariad again some time. I think the problem is that I grew up, but Eddings' writing didn't. He simply does the same thing, in different settings, over and over again, and as a result, The Domes of Fire hit my trash bin. The same inane banter between the characters was getting so tired, I wondered "why the heck am I reading this stuff?" It was a frustrating waste of time, so I stopped.
Instead of Eddings, I have graduated to GRR Martin, Raymond Feist, Janny Wurts, Steven Erikson, Neil Gaiman and Patrick Rothfuss, among many others, whose writing is grown up and challenging to the reader. However, I will always have a soft spot for Eddings and The Belgariad. Fantasy has grown a great deal in the last twenty-five years, but that series was just plain fun, and it is a modern fantasy classic, though the test of time has been a bit harsh on its staying power.