Firstly; watch out for plot spoiler reviews!! (it's not a mystery tour if you know where your heading)
Egan's work is 'Hard' Sci-Fi of the highest order. I give him the edge over Brian Aldis (my other favorite), as concepts are heavier and plots driven by 'rawer' science at a blistering pace.
His breadth of vision astounds; always extrapolating logically to the n'th degree. A modicum of effort may be required from the reader at times; but one is richly rewarded with a sense of awe, discovery and achievement. Each book is a Grand Odyssey.
Hold tight and don't look down, because he'll take you a long, long way from where you started....