I came across a short review of Seveneves on GatesNotes a few days ago, and picked it up quickly on my next Crossword trip. I had read Quicksilver by Neal Stephenson earlier, and had read about 2/5th of System of the world, but then this third part of the Baroque cycle had proved too baroque for me. Nothing of this sort happened with this one, and I found much that is delightful. First of all, this novel belongs in the best traditions of SF, containing a lot of actual science. There are pages upon pages on Orbital maneuvers for example. Same is true (to a lesser extent) about epigenetics, heterozygosity and robot swarms. The characters feel real (they use Python to program their robots and parse logfiles after all). And the book manages to be consistently readable, through all of its Eight hundred and sixty six pages (OK, parts of Part III are a little flat, but that is really little). I came back to SF after a while, and reading this book felt like a breath of fresh air. I certainly see myself returning to it.
P.S. While searching for the link above, I found a longer (and frankly better) review on GatesNotes. Do read it.