For a first nightly build available, it runs surprisingly well and some of the main functions such as telephony, WiFi, camera and the main customization options seem to function just fine. As for the performance, it is buttery smooth. If you are planning on upgrading from CM10.2 I would highly recommend you give this build a try.
The custom rom is available for LTE (GT-I9195) and 3G (GT-I9190) users and it can be downloaded from the official cyanogenmod website, there is no build available for the Duos users unfortunately. Links can be found below.
CyanogenMod11 for S4 Mini LTE - Click here.
CyanogenMod11 for S4 Mini 3G - Click here.
Gapps for CM11 S4 Mini (LTE and 3G) - Click here.
- Rooted phone
- CWM or TWRP recovery
- Download the appropriate zip file depending on your model to your sdcard
- Download the Gapps zip file to your sdcard
- Power off your phone and hold the Power + Home + Volume up buttons simultaneously
- Choose wipe data/factory reset
- Once that is gone, choose install zip
- Then choose install zip from external sdcard
- Locate the cm11 zip file and choose it, then choose Yes to confirm
- Re-do steps 5 and 6 but this time choose the Gapps zip file
- Once it is installed aswell, press the back key until you get to the main menu
- Choose reboot system now
Source: LTE xda thread | 3G xda thread