SAO volume 20 read:

This was an unsatisfying book.  It has no conclusion.  It answers nothing.  The enemies are still on the loose, their identities and objectives unclear.  For that matter, this entire plot is severed from everything else -- Kirito and Asuna are stuck in another world away from both friends and enemies for 200 years, which they'll all forget once they wake back up into the real world.  You can't get much more 'side-story' than that.

There's only really two good scenes in the entire volume.  One is Asuna reflecting to herself that she feels guilty about monopolizing Kirito when so many girls love him, but also relieved that all but one (Ronie) are now out of her hair.  It's nice to see the problem with SAO addressed head-on, which is that Asuna isn't the only girl with a rightful claim to Kirito's affection.  Strangely enough, it seems that Asuna understands this, but Kirito himself doesn't.  He isn't in the least attracted to or interested in any other girl but Asuna.  It isn't even at the point where his soul heroically struggles to withstand temptation in order to be faithful, he acts like they're pieces of furniture that couldn't possibly be enticing.

I suppose there are people like that, who are only attracted to their soulmates.  Certainly that isn't how a normal boy feels about cute loving girls, but there has to be one or two who feel that way. . .

It's a little amusing that Asuna feels more guilty about the situation than Kirito himself.  It implies that Asuna could allow for polygamy if it were just up to her, if only Kirito weren't so dense that his feelings never extended to anyone else, so the whole project would be pointless.  Asuna was already mai waifu but this insight into her character makes me think even higher of her.

The other good scene in the book was Ronie kicking ass and taking names in the mansion alongside Tiese.  I feel like Ronie takes after Kirito in a lot of ways, including her prodigy like fighting skills.  She really is his disciple.  She's the female Kirito.

Two good scenes in an entire book is pretty sad, though.  If it weren't SAO I wouldn't recommend it, but since it is SAO it's necessary for the sake of understanding the future volumes.  Moonlight Cradle and Unital Ring have no anime, so all we can do is read on, good or bad, for the sake of getting to know the ending.