I noticed several problems when installing the device driver package. Some of them exist between all versions, while others are specific to the latest package, v.2.1.5.
 
There are as follows:
 
1. The installer does not properly request administrative privileges before attempting to write to non-userspace folders such as "c:\Program Files (x86)." It seems to just barf files all over the place with no respect for the permissions of the current user.
2. The installer does not properly terminate running executables/services before trying to overwrite them. This results in many required files failing to write, and if the user is upgrading from a previous version there will be mis-matched file versions, causing the driver, services and other executables to fail to load with cryptic errors upon reboot.
3. The installer package prompts the user to reboot before it is finished writing files. Three times. Once after it finishes trying to install the driver (via a message bus notification); again after finishing trying to write the driver files, and again after trying to write the application files. It doesn't seem to care if the files were written successfully. If the user reboots at any of these prompts the installer will choke and die leaving the user with a broken installation. In order to finish the installation the user has to not click the notification to reboot and then say no when prompted to reboot twice.
4. The installer does not CRC check the firmware before loading it to the sound card. This is awful for a multitude of reasons, not the least of which are that a broken firmware file can brick the device because it uses a firmware-based loader to load the binary blob. Also it's possible that without a CRC check a malicious firmware could be loaded.
5. After an install of the driver package and a reboot THE VOLUME CONTROL is SET TO 100%. If the user is expecting the volume to be low because they are using an external amplifier, this could destroy their equipment and/or their speakers, or cause hearing damage.
5. On boot the NU application tries to write an initialization file to a non-userspace folder without requesting admin permissions and then complains that it did not "properly initialize," when in fact it did initialize properly and there is no need to write the file to begin with since the settings are stored in the registry.
 
Not to sound too harsh, but this installer looks like it was written by a toddler who got dropped on his head just before sitting down to code.
 
In order to ship this installer you would have to run it, see it fail, then intentionally ship it broken because it would be impossible for it to finish successfully even under the most ideal conditions.