First: I read all 6 Books from the series, so my review is actually about the whole series rather than only Parts 1-3, since it is hard to just review only parts. Sorry also for the english, not a native speaker ;)
I like the idea of the future world, that is depicted in the story. Its plausible enough, technical stuff is minimal, just as needed. I like that part. Maybe a little too much "pulse" here, "pulse" there, but still ok.
I had some trouble with the characters, or rather the method of description. For me, a picture of the character is formed in my minds eye pretty soon, but here I had some problems with that. Characters were not described much at first, but some characters will be described in more detail much later, so my mind picture needs major adjusting. In that respect the characters are described comparable to the gradual increasing depth as the technical innovations, but what works really well for the tech does not work so well for the characters. Some get never well explained or have rather unexplainable mood changes - maybe that is intentionally as a teen sees the adults?
The storyline as a whole is pretty suspensefull - not too much, and some developments are quite obvious (like the romantic developments between the teens) - but as a whole nicely done. Sometimes though i got the sense of something not completely thought through or not finished or not polished enough.... its hard to describe, but I try... (i try not to spoiler, so it might read a little cryptic here) e.g. the Showdown of book two was rather abrupt, the suspense here was minimal, the enemies too dull. Some rare scenes are also just plain confusing - character names get mixed up, or it is not clear who is doing what, saying what. Some problems also go away too easy, like some troublesome characters dying along the way... so, some story-elements are solved too cheap.
Being a non-native speaker (and having read in english) I totally love the different language levels that get depicted here. You have the plain adult language, the modern teen language, the near-future chat language, and even the old-style language from 1900s. Especially the dialogs per Pulse-Chat-Messaging are a nice touch - although here the same problem arises as with the characters: you sometimes don't really know for sure who is writing, because you dont know the last names yet, but the messages are signed with initials... but you get the drift, still, also here a little of an "unfinished" feel.
My CONCLUSION:
Although some things have a touch of not finished or polished enough, the story as a whole is still suspensefull, and the general idea is really nice. For me it was nice to read a kind of american youth language, because I just like language to that degree. Also it was nice to get a feel of american morales, e.g. the handling of "PDA" - I was in the US for two years, but that explained a lot in hindsight.
I deducted two stars, because of that unfinished feel and because of some cheap "happy"-endings.