As for the Ark of the second book. I had a hard time believing that with most of the world flooded we could pull together the resources to build an interstellar spaceship. Even if all of the separate technologies involved had already been developed just getting it all built and working would be near impossible. They had to build 100's of nuclear bombs for one thing to launch the ship and then stop it again around Jupiter. I say 100's, but Im not sure exactly how many. I remember it being 1 bomb every other second for some amount of time... And then the anti-matter they needed! They had 4 years to make all they needed using a particle accelerator they scavenged from under the flood. Seriously, Im betting on 10 years just to get the thing running in a non-flooded world. And when that idea went bust, Oh, lets just mine the radiation belt between Jupiter and Io, no problem! And at the heart of it all, the Alcubierre warp drive. They have this genius Asian scientist who keeps saying "Oh wait, I seem to remember..." then he goes back to some research paper he remembered reading about before the flood. Lots of that going on.
The last thing, the worst for me, was the ending. All through the books when some milestone of the flood had been reached you had a select group of fortunates that were able to be saved and move the the next 'level'. At each of these it was very heart wrenching, good people left behind, families split up. Even when the Ark launched it was all chaotic and the crew wasn't as planned. But all that was just setting me for a very emotional 'happy' ending that I was really anticipating. But No. The story was setup so that even when we do reach Earth III, only so may can go down to the surface. 3 adults and 37 kids. Thats who is going to repopulate humanity. And the adults all had to leave their wives and children in orbit to die eventually couped up in a stinking, failing tin can. No one sent down could be related to each other. I was pissed! And one of the adults was Wilson! He captained the ship for a long period of time and took 13-14 year olds as lovers and beat the crap out of them when they got old enough to rebel. Well, screw all that, I wrote a much better ending in my head to substitute for Baxter's crappy ending:
OK so the only remaining shuttle/glider could bring down 40. But instead of the rest of them wandering the solar system until life support failed, they found a way to convert the entire ship into a ad-hoc lander. They had a machine shop, they could have whipped up a simple glider to hold everyone else for a short time. Then use the rest of the ship as a sacrificial re-entry sheild, once down into the atmosphere enough the glider could be launched. Very risky, but much better that the alternative. Of course it works and all the families are reunited on the surface! Oh yeah, and Wilson had to pilot the sacrificial ship giving his life to save the rest of the crew. Yeah, happy ending!