Liminality is interesting - as it deals with what's happening in the real world as opposed to staying completely within the game itself. It's also the shortest, being an OVA of just 4 episodes. The music is, as usual, quite techno for the most part (thought less so than the rest of the franchise), appealing to some people but not others - but I am one of the former. Unfortunately, that is probably the most appealing thing about the series, unless you love the seiyuu of course.
.hack //ROOTS basically gives viewers the backstory to the .hack//G.U. game - covering the time that Haseo spent in the Twilight Brigade, and I guess, giving him an objective that has to be achieved in the game. But it's damn slow, it probably shouldn't have been a 26 episode series. And of course the ending was unsatisfying,unlike .hack//SIGN, because it was always intended as an introduction to the game.
The problem with the .hack series is that you have to play the games to get the most out of the franchise. And I will never play them, so I don't know whey I ever watch them. Even listening to a particular voice...or rather, several, barely got me through this one.
Back to watching the the Honey & Clover movie then.