Here's some thoughts about the movie from me:
I liked the start where he just drives along the city, I was confused why he shot at the figure through a window since it was obvious he wouldn't hit at all.
I liked that he was getting a bit crazy talking to himself due to living isolated for years.
I didn't understand why the other people didn't contact him earlier or why the girl run away from him when he spotted her. Since they knew of him, who he was and what he was trying to do.
I thought that the romance was a bit rushed and maybe forced. But it might have just been to demonstrate that they were both extremely lonely.
I also didn't understand why the mutants were having so many problems dealing with him. His house wasn't that fortified, all they had to do was to burn the house to the ground with him inside (since they liked fire so much). I guess the lights did keep them away at a distance. But they could have just pushed trucks and cars and blocked his way out (we see them doing that while he is driving, pushing vehicles in his way).
I don't understand why he left the girl go to the city by herself, especially since he even got warned before that some people "turn" really quickly, in a matter of minutes or seconds. So he would have wanted to monitor the girl, he even says that no one knows when she would "turn".
I don't get why they could kill Richie just there on the spot but had to go through all the bullshit to bring whatshisface to the stadium to burn him alive when they first got a hold of him.
It was because they considered him a special case, since he was a scientist working on vaccines and stuff. They considered him one of the people who actually brought the plague to the world and kill it. So they wanted to purify/destroy him by fire.
Yeah, it was stupid. But the mutants weren't very smart, to begin with.
I thought the end was a nice symbolic piece of art. He died for humanity's sins (the plague and the mutants) so he could save humanity (with his blood) with open arms, kinda reminiscence of Jesus or something.
Overall, I enjoyed the movie.