I've only played this one SAO, and it definitely wasn't worth it for me.

I don't see much of a connection to .hack either -- but again, I've only played the one game that's on Steam, and that was another thumb-down...

I wouldn't focus too much on both games building around a VR theme -- for me, the only connection was that they both suck.

It's definitely side-content, though. Characters keep talking about stuff they've done in the past (no idea whether its the anime or the other games), and there's basically no actual story.

And then the side content has side-quests... I think its the first game ever where I just skipped through the dialogue because its so utterly pointless...

Still, if the characters already mean anything to you, and you know what they are talking about, then maybe it's more interesting for you.

Gameplay seems to be focused on the DLCs, which I didn't try. Until then, there are no skills or anything to develop.