I've given it 4 stars only so that I can later give 5 to the sequel, A Fish Dinner In Memison. (The third book, The Mezentian Gate, though there is enough to be well worth reading, was tragically incomplete when ERE died. It's bits in the middle that are missing.)
ERE's first fantasy work was The Worm Ouroboros, utterly wonderful, but these Zimiamvia books soar to new heights, not only in things such as prose, intrigue, characterisation, but also and more importantly in their phenomenal ambition. ERE creates not just a world but, as is gradually revealed, an entire philosophy underpinning the universe. He's the closest thing in fantasy to the visionary Olaf Stapledon, able to steal your breath away with IDEAS alone!
The writing is intense, lyrical, dense, archaic and just UTTERLY fascinating. This is not straight entertainment a la David Eddings, it requires you to engage with it in both mind and soul; but for the serious reader it is uniquely rewarding. (Though John Crowley's even better!)