Hmm, so I'm just finished and I have to say my overwhelming feeling toward Anathem is that it was just really dull, too long with too many made up words.
There is a pattern throughout the book that goes something like this:
"Erasmus goes to a new location, he meets new people, he learns something new, that may or may not be tangentially related to the larger quest, but which also involves long side arcs where not much interesting happens". That is repeated at least 8 times if not more (interviews, apert, punishment, travel, city attack, archaeological site, new Math, space, ship, finale and probably a few more i missed).
The characters seem quite one-dimensional I thought, Arcibald and Jezry are almost interchangable. We are told multiple times that Jezry is the most gifted in the group yet never see him do anything to justify the acclaim. The love story could be removed and felt like an annoying add-on with no depth. None of the characters felt like actual people, merely plot devices that deliver some new information which sweeps our hero on to the next plot point.
It just seemed to me that it took an extraordinary long time to say nothing at all really, I would guess if someone had studied philosophy and was interested in a discussion about Nominalism and Platonism then it will tick some boxes but for me it didn't really work. It all just seemed a bit preachy, I'm sure there is a trope for characters who use a form of didactic conversation to withhold secrets until the student is ready but its probably used too much here. I may have drifted off a little towards the end, after the 3 way end story stuff, and missed some glorious reveal...
I don't feel it come close to the scale of Cryptonomicon which had multiple timelines and multiple perspectives wrapped up in an admittedly more firework laden storyline. Anathem is a single perspective wrapped around one topic which starts to really drag when we hit long wordy chapters filled with philosophical navel gazing.
Twas OK, maybe 2-3 stars out of 5. I'm coming to Anathem after reading the fantastic Wolf Hall/Bring Up the Bodies books from Hilary Mantell, who really knows how to build a character, so perhaps I'm treating Anathem too harshly as the comparison highlights its failings more acutely.