I thoroughly enjoyed reading these four books. Nice plots, a lot of cool technologies but also a lot of thoughts about their potential dangers. Interesting characters, that come back from one book to the other, so it is nice to see them evolve in time.
All books can very well be read as standalone, no cliffhanger at the end, but it is very pleasant to come back to the universe to discover more in each book. Some books focus more on some characters, so I preferred some of them, but I still enjoyed reading all of them. And I'm very much looking forward to reading the latest book in the series (Inhuman) that was just published today!
If you like sci-fi you should give it a try and download a free sample. If you like it, then this edition is a great way of getting all four books at a very low price (at least at the time of my review).