I don't see how it works to present long discussions among the aliens, as supposed revealed messages sent. Why would the aliens send the humans a short story presentation of what they thought?
Also, they aren't really aliens, just humans in alien skin (and given we don't read about what they look like in book 1, they are just humans).
The protagonist isn't that interesting, although this is more subjective, certainly. The idea of destroying the entire world because humans harmed you is rather nice, but imo not very believable as it was handled.
The Sophons are less practical as well when revealed - why on earth would they reveal their existence at all? Maybe there is a convoluted reason, but it makes no sense to do it. Maybe it was just hubris or whatever