CyanogenMod is an advanced open source firmware distribution for smartphones and tablet computers based on the Android operating system. It have unique features and options which are not available in the official firmware distributed by vendors and maufacturers of these devices.
These features include native theming support, FLAC audio codec support, large Access Point Name list, an OpenVPN client, an advanced reboot menu, Wi-Fi support, Bluetooth, USB tethering, CPU overclocking and other performance enhancements,
Supported devices are listed as supported on website cyanogenmod.com/devices. If a device is not listed in cyanogenmod website, then installing cyanogenmod on it have certain risks associated with it listed as follows.
Mobile device hardware may likely not have proper drivers. If it shares drivers with other devices then it may work, but otherwise various parts of the hardware will fail to function.
The partition layout may be different, which could cause the installation failure if partition sizes and format are very different.
The kernel may not work properly on device's processor. For device's processor, it doesn't it depend on the architecture. if it works for one ARM device, then it also work on other devices.
The boot image may not be configured and packaged properly for the unsupported device.
CyanogenMod is basically an alternative operating system intended to replace the pre-installed OS on smart phones and tablets. If an older device that isn't getting updates anymore, or if the device seems unusually slow, or it have unwanted spyware, adware, then installing cyanogenmod may bring performance and security updates to resolve these issues.