I started X-link on a whim, and I was surprised at its quality almost immediately.  This post is basically a composite view of my impressions up through the Chiruouka (bad) ending that lies roughly two-thirds of the way through the game.  

X-Link uses the ladder-style structure made popular with G-senjou no Maou and Aiyoku no Eustia, and we all know my general dissatisfaction with this particular structure, so I won't go back over it.  Instead, I'll focus on the parts of this game that exist aside from this issue.

This game is set in the year of 2050 and onward, in a world where most military activities are carried out by three great PMCs (Private Military Corporations), and most of the world has gone to crap, even as technology has moved forward immensely and at a rapid pace.  Human-like automata/androids are already in common use in service professions (Nurses, waitresses, airline stewardesses, housekeepers, etc), and they've more or less come to be accepted as part of the scenery.  That said, they are often the target of human spite and arrogance, and, considering that they possess emulated emotions, this can cause problems.  Recently, the first fully genetically-modified humans called Edited were released, but the release is considered a failure, as only a small portion survived to adulthood (by accident or design, it is not really spelled out at the point I'm at).  

Before the beginning of the story, the protagonist's older sister, who was considered the penultimate Edited, died in an accident that leveled her laboratory and left him in a depressive funk that lasted several years.  He is broken out of that funk by the arrival of Himefuuro, a fully autonomous android designed with the ability to share emotions with humans through a kiss.  By sharing his emotions with her and feeling her unconditional love for him, he is able to break out of his depression... only to become rather obviously dependent on her.  

X-link has five heroines:  Akira, Hina, Chiruouka, Yuuri, and Himefuuro in order of their endings.  Akira is a teacher and agent (this isn't a spoiler, since you find this out in a 'her perspective' scene early on) who infiltrates the school the protagonist attends as part of her hunt for something involving the corporation that runs the school.  Hina is a girl with an incurable disease called Coppelia Syndrome that causes the skin of the afflicted to harden gradually over time until it kills them.  Chiruouka is a rogue combat cyborg and the only third generation cyborg other than Himefuuro in existence (second generation being the ones currently used, who are completely reliant on the giant central servers to maintain their personalities).   Yuuri is an Edited girl with a tendency to lie for the sake of lying who shares the exact same appearance as the protagonist's older sister.

The story of this VN is generally serious in tone.  Most of the characters - heroines and protagonist included - are deeply scarred and somewhat warped personalities.  The story itself constantly revolves around AI issues throughout what I've seen so far, ranging from the classic identity crises to what happens when androids find religion.  It is interesting enough intellectually for me to take an interest that way, and the complex emotions and motivations of the characters grant the game a pretty good degree of depth.  That said, the protagonist is dense as the hull of a warship and generally inexperienced in human relationships that aren't 'family'.  As a result, some of the conflict in the story is centered on problems caused by his generally thick skull.

While I'm reserving final judgement until I finish the true ending and go back and play the other heroines' endings, I can say that the journey so far has been worth it, and the writer's approach to AI issues has been more thoughtful than I anticipated.  As such, this gets a tentative recommendation from me.  This game is pretty long, and my stamina just ran out, so I'm going to take a week or so of 'vacation' from it before I go back and finish it up.