The historical setting (French Revolution) and the inclusion of prostitution and rampant classicism may give you the impression that Gerard to Jacques is a dark, heavy tale. While there are some dark moments (and twisted characters) here, the storyline contains plenty of lighthearted scenes to keep you happily skipping along with Gerard to Jacques from beginning to end. Now, that may appeal to some of you....
...but in fact I think the lack of gravity turns this potentially great story into a mediocre one. Some major elements of Gerard's painful past receive just a light touch-up, even though they merit a more thorough explanation. The tone of the last chapter seems at odds with the heart wrenching episodes leading up to that anticlimax. And although the author made a valiant effort to explain the Reign of Terror and the political machinations behind that outbreak of violence, the Terror lacks any concrete presence in the storyline. So what we get is a bunch of characters sitting around and explaining, for several pages at times, what is going on with the Robespierre and his band of bloodthirsty executioners. The sense of danger brought on by the Terror is effectively blotted out - and it remains a distant thing, which muffles the realism of the story.
I do like the characters. Even the villainous ones - they are interesting and well-developed and I think their relationships occur naturally (and in Gerard and Jacques' case, rather touchingly). I'd like to point out, however, that there is a random time skip at a crucial moment in Gerard and Jacques' relationship that left me a little bewildered.
The weaknesses in Gerard to Jacques give me the overall impression that the story was rushed. Something like the mangaka had planned a more lengthy storyline but the editors cut the series short. Perhaps if the author had been given a few more chapters to unravel this story, we might have ended up with a true gem.