The Nexus 4 came out and really turned the smartphone market on its head, but it didn’t penetrate the market as much as most hoped. The Nexus 5, will have the same fate, unfortunately. This is due to Google not marketing the phone strongly enough, and it has to compete with the juggernaut that is Samsung.
The Nexus 4’s main problems were no 4G LTE connectivity, a sub-standard rear-facing camera, and a few other niggly issues. The Nexus 5 corrects these problems, with 4G LTE connectivity, and a much better camera. I’ve read some other reviews, and most reviewers don’t think the Nexus 5’s camera is all that great – but from my time with it, I love it.