Peter F. Hamilton doesn't get a ton of praise for characterization (and I found his latest novel strangely, uncharacteristically vulgar and puerile), but I think he has a lot of the chops that Tschaikovsky lacks -- especially when it comes to language. Tschaikovsky's writing is at times awfully clunky. Hamilton's prose, by contrast, in my view at least, is in its own category among living sci-fi writers for its polish and effective use of the countless tools the language offers.
Unlike the others, I think Tchaikovsky's best writing is in Children of Ruin. I know it's not as popular as Children of Time, but I admired the way he didn't rinse/repeat and instead created a wholly different view of humanity's legacy intersecting with alien life. I though the "antagonist" in that book was far more alien and creative.
You're absolutely right that female characters are, uh, not his strength, and mostly I think you must be right about characterization in his work as a whole. That being said, when I ignore the male characters who seem like wish fulfillment of some adolescent power fantasy (Nigel Sheldon -- immortal genius, intergalactic industrialist, undisputed patriarch, and virile keeper of the harem? Please.) and the female characters who are, you know, young, "nubile," and hyper-sexual, the remaining roster is, I think, solid. Even the characters who are archetypes worked for me.
(Edit: sorry, I confused Children of Ruin and Children of Memory.)
And I find myself agreeing with your assessment of Children of Ruin. In some ways I think it's not well constructed, sort of stumbling through the mystery, winding up much longer than it needed to be, but the main character (no spoilers) has a psychological richness that I can't recall encountering in his other books and is the only of his characters to whose fate I've felt emotionally attached. The ending, too, is among the best and most affecting I've read in quite a while.
And, yes, the antagonist and setting is, I think, incredibly well conceived and well drawn.
So maybe I've changed my mind. Despite some structural issues that, I think, weaken the novel (and I think recall feeling that the 'reveal' came too early or just that the clues leading up to it were too obvious), it may be my favorite book in the series. Its more modest cosmic stakes and narrower field of view, than a lot of the other work of his that I've read, enable Tschaikovsky to develop it into something quite special.