Story
The .hack series isn't an easy one to get into for those of us who haven't played the game as there is plenty of background information that is left out in the anime. The strength of Liminality is it addresses some of these questions in a very intriguing manner. Liminality spans more than one .Hack anime, several of the manga and some games but the genius in this anime is it does so from the Real Life point of view (vs. gameplay). It manages to tie many loose ends together and in an entertaining fashion.
Characters
The characters are well fleshed out and developed. There is no sense of incongruity that these people don't behave like normal people would behave In Real Life. They're realistic and believable. Even the backstory characters of who developed fragment and why, is lovingly done. Overall, very solid.
Art/Animation and sound
Opening theme showcased the game in a very persuasive manner. If the game graphics looks anything as good as what's presented here then more people will play it. Character animation was clearly of a higher quality than .Hack/Sign or .Hack/Twilight. Sound effects are wonderful, music is good and even the insertion of the Hack/Sign theme was well done. Again, this was solid.
Enjoyment/Overall
Story wise, this has been the best of the .Hack anime I've seen so far, probably for the "summation" nature of this ova. It didn't feel too short or too long, there was no "filler" type material. The plot was tightly woven, pacing was great and thus I enjoyed this much more than the other .Hack series I've seen. Very very solid and good. I would have rated this higher if I were more familiar with the manga or played the game.