SAO Progressive volume 8 read:

This was an excellent novel (with excellent illustrations of Asuna in a bare-shoulders but long sleeves black evening gown and a one-piece white swimsuit).  I could read about the silly adventures of Kirito and Asuna all day.  Sadly the book ended quite quickly and there's no volume 9 out even in Japan.  This time the book covers slaying a dragon, Kirito becoming a vampire, and winning big at a casino.  As well as kidnapping a pet monster. . .quite the free range of activities going on, but all very fun.  It really does feel like a game come to life utopia.

Progressive is still on the 7th floor of Aincrad, out of 100.  The author cannot possibly live long enough to cover the entire trek up the tower.  At some point he'll say 'and their adventures continued' and call it a day, but I hope he writes a lot more volumes before then because they're phenomenal.  I think better than the real SAO novels.  In the real novels, there are so many characters and so many complicating factors it's hard for Kirito to get anything done.  In Progressive all he has to do is romance Asuna and defeat the floor boss so he can reach the next floor.  The story is always 'on target.'  I like all the side characters in SAO, but they don't measure up to Kirito and Asuna, so the story always takes a dip in quality whenever it leaves the main characters behind.

Also, in Progressive, there aren't any 'cheat' abilities like incarnation which let Kirito do basically anything in Alicization, or be overpowered like in Alfheim due to his character starting at max level, etc.  Everything he does in Progressive is earned the old fashioned way, by wits and hard work.  Kirito also feels more natural, playful and less emo, in this series.  In the real SAO books he's always condemning himself over some stupid thing or other.

There are good things about the non-Aincrad arcs so I don't want to be too hard on the main series.  Unital Ring is also fun.  But Aincrad was a magical moment in this story that so far hasn't been matched.  Progressive returns to that magic.  It's that simple.