Transcendent is a novel of massive ambition that only partly comes off. We have another narrative split between two times, this time spanning a "mere" 500,000 years, one a future human and her family in a generation ship, and a present day narrative with yet another Poole (Michael, nephew of George from Coalescent) initiating a massive geo-engineering project to combat global warming.
Future figure (Alia) gets called into a project/entity called the Transcendence, which is nothing less than an attempt to produce a coordinated super-mind that will take evolution beyond humanity all together, and in the middle of this she maintains an interest in Michael Poole that grows to be the heart of the novel's resolution. The Transcendence sounds a lot like the sort of awakening of a group mind listed in Olaf Stapleton's classic "Last and First Men" and Baxter has noted his admiration for Stapleton. There are also echoes of Frank Tipler's ideas explored in "The Physics of Immortality" of future humans trying to redeem those in the past.
Just as Arthur C Clarke's novels are heavily Buddhist influenced, Baxter's lean heavily on his childhood Roman Catholicism, hence his obsession with martyrs, saviours, resurrections, a pessimistic view of human nature and even bodily functions. This is his most explicitly Catholic novel yet; indeed redemption (with a capital R) and its means and significance is a major theme of it. Rosa from Coalescent makes a reappearance, this time as a (female!) Catholic priest, almost as a means for data-dumps on obscure (but relevant) Catholic doctrine and ritual.
The novel can be slow, Michael Poole is even more of a self-pitying annoyance than his uncle George in Coalescent, slabs of philosophical and theological thought are dumped straight at you and characters can be ciphers. But if the novel's a partial failure, it's a failure of over-ambition. It's far from perfect, but I've read few SF novels that have dealt with such lofty themes and asked such fundamental questions.
(Mild spoiler). There is a thread linking all three Destiny's Child novels (apart from the appearance of Coalescent human colonies in each) - all feature a new type of human society where the individual is a cog in the whole. The Coalescent in Coalescent, the society of child warriors at perpetual war in Exultant and the Transcendence are all ultimately dead ends. If there's a message of the series, it's that we're left with our flawed individuality as the least worst option. (end spoiler)