This felt like a book aimed at an audience that was not me, which I think was an accurate feeling. I definitely felt like I needed more formal training in history (I dropped it pre-GCSE at school), if not Egyptology itself, to get the most out of the book. But even so, it was readable providing I broke it up into chunks rather than try to assimilate too much at any one time, and I think I followed the overall ideas behind the book even when I was bogged down in the details. Assmann divides the evidence for their world view & history into three types - traces, messages and memories. Traces are the archaeological type of evidence, from burials, buildings, bits of pottery etc. Messages are the things the people write down about themselves - the things they wish to tell the present and future about themselves, so inscriptions on temples of the King smiting his enemies fall into this category. And memories are the stories they tell about the things that happened in their past, which often tell us more about the present than the past they are pretending to be about. Like the Middle Kingdom insistence on the Pharaohs of the early Middle Kingdom as bringing order from the chaos of the First Intermediate Period - there is some historical truth to it, but it is also an important part of the justification of kingship in the Middle Kingdom.
I found the alien nature of the Egyptian relationship to time and their (linked) concept of order & chaos one of the most interesting things about the book. As I mentioned above they saw time as essentially cyclical - events don't just happen once, they are repeated and repeated throughout history. So the King smites the enemies of Egypt, and he doesn't do this once and they are defeated forever, no he does this again and again - the smiting of the enemies is part of what it means to be Pharaoh. And it is part of the way in which the people bring order (or ma'at) to the world and thus ensure the continuance of the gods intention for the world. Temple rituals are part of this - they are done each year as they were always done (obviously it does change, but the intent is to keep doing the same) and this is what keeps the world as it should be. Over the length of the Egyptian civilisation it does begin to change - for instance Ramesses II records specific battles in his temple inscriptions, rather than ritualising it to a more generic "smiting of enemies". And around & after that time dealings with foreigners are again more specific and less isolationist. But temple ritual keeps on its insistence on the cyclic nature of all existence.
One of the things I got on less well with in the book was the constant comparison back to & reference to the Bible and the Christian traditions of thought (although he talks about it as Jewish or Judeo-Christian at various points, I think it's intended to be the Judaism that's preserved as a memory in the Old Testament of the Christian Bible, not modern Judaism). I think this may be Assmann's "thing" - he has, I believe, another book about Moses & memories of Egypt - and may also be intended to give the audience more familiar hooks to hang the less familiar stuff on. But to be honest I found it more jarring than useful.
I think it was well worth my reading this book, but I'm not sure I'd recommend it per se - I found it a struggle to get through at times (hence taking me 6 months) and unless you have either a strong interest in Egypt (like J, and me to a lesser extent) or more education in history than I do then I think it might not feel like it was worth the slog in the end. It has, however, changed how I look at both history in general and at Egyptian history. The division of the evidence into three types feels an obvious way to think of it in retrospect, but I'd never thought of it quite like that before. And the insights into the Egyptian concept of time (that I mention above) and their concept of social structure were very interesting.