I just finished this series. It seems like the type of series where you would get something out of watching it a second time.
The first half was pretty amazing. The end of each episode left me badly wanting to just marathon everything. Lil ("Re-l') was a great character, the premise was amazing, and there were many mysteries to be solved. The second half took a different direction that, while interesting, had a very different feel. Notably, the series seemingly tried to present a few philosophical questions to ponder, but I didn't feel that they connected. Maybe it was just me.
I generally try to avoid analyzing series from a production standpoint, but there were two things that really bothered me as I watched them. The first was episode 15, the gameshow episode. It came out of nowhere and left the same way, but what really bugged me was the way that episode was used to explain a fair bit of backstory and introduce the concept of Proxy One. Maybe it was supposed to be a bit of comedy thrown in and I just didn't get the joke, or maybe I just don't appreciate game shows like other people do, but to me it seemed like lazy storytelling. Surely there could have been a better way to make that information known to the viewer.
I'll admit, the ending also bugged me. In many ways it was well done, but it made all of the mysteries of the series seem pointless.
Spoiler for Ending discussion:
The "big reveals" in the series are:
1. that the Proxies are made by original humanity ("the Creators")
2. that those Proxies made the domes, that those Proxies are required for the artificial womb system to work
3. that the artificial womb is actually a living creature (based on what I've read, there's some debate over whether these creatures are Proxy-made or if they're remnants of original humanity that didn't make it into space, and that have been mutated by the environment)
4. that humans produced through the artificial womb system are sterile ("half human")
5. that Proxies will die when exposed to sunlight
In other words, we have this fantastic setup that will be completely obliterated without Proxies, and all Proxies are designed to die once the planet is healed. Once the planet is healed, original humanity will return to Earth. Given that the "half humans" are sterile and will die out with the Proxies, and given that neither the half-humans nor the Proxies are working to restore the planet, what was the point of their existence? Why even bother to make these elaborate things in the first place?
The answer, according to one person's comment, has to do with philosophy. Echoing the old "if a tree falls and there's nobody around to hear it, does it make a sound?" line of thinking, original humanity worried that the planet either wouldn't recover or would cease to exist unless someone were there to witness it. Hence, Proxies. (They made it sound as if this was mentioned in the series, but I don't remember it being stated - especially not that clearly.)
Even if that's what the series truly intended, such a reason is still a bit of a downer. A large driving force of interest in the series has to do with figuring out the mysteries behind the Proxies and the world, but in the end it seems as if the reasoning didn't live up to expectations. I'd still recommend this series to others, but it didn't make it to my "favorites" list, even though it seemed to be heading that way based on the first ten or so episodes.