I played KQ7 back in 1998 as it was included in a magazine to promote MoE. I never got very far, and my only memories were of a woman in a green dress wandering through an endless desert crying "Rosella! Rosella! Where is my Rosella!?"
It's a pity I never played any of the other KQ games as a child.
In any case, GOG.com had a sale on all the King's Quest games in about April 2011, so I did a bit of research and decided to buy them all for half price. Since then, I have been slowly playing through the entire series from start to finish. I'm really really loving it. I have just completed KQ7 and started MoE.
It has been weird condensing ten years of game development into a single year, but I've really enjoyed the graphical and gameplay changes over the course of the series. I played all three versions of KQ1 and I think the best part was when Graham looked in the mirror and saw himself on the throne (not sure which versions had that). The ending of KQ3, once you arrive in Daventry and get to explore parts of the first game. Hating, and then growing to like the owl Cedric in KQ5. Pretty much all of KQ6 (I'm still saving up the "short path"). I'm a bit torn about KQ7 -- it was so different and the puzzles so silly, but I still liked it overall. MoE is pretty grating -- I don't so much mind the different gameplay, nor that the main character is not a member of Graham's family. What is more annoying is that they have almost entirely abandoned all of the places and characters from the other games. But I'll keep playing it.
Looking forward to seeing what Telltale can contribute to the series.