Some of the issues included buttons that had sharp edges and would wobble in place, SIM card trays that didn’t slot into the phone properly, and small microphone and speaker grills causing poor call quality.
To remedy all of these problems, all new Nexus 5 models that will go into production after today will have an overall changed chassis. The new Nexus 5 models will include fixed buttons that are both more comfortable to press and fit in the phone firmly, and a new SIM card tray that will fit securely in the phone.
On top of this, a larger grill has been cut into the chassis of the phone to allow sound to travel out of the speakers and into the microphone easier, which should solve any problems people may have had with call quality in the past, and will also improve audio quality for music and videos too.
Although these changes have been put into place already, if you buy now you may still end up with an older model as Google will still sell off the first generation before moving onto the new Nexus 5 handsets that have a more durable build.
According to various sources, most of the leftover stock is concentrated in the 32GB white version, so if you are hoping to get the newest production model, you may be better off waiting a few weeks if you wanted to get the 32GB model in white, and waiting a week or two to get the black version in either 16GB or 32GB.