This phone comes out of the box with a slow Touchwiz version of Ice Cream Sandwich. The best ROM I’ve found for it so far is Cyanogenmo http://www.awgolf.co.uk/Ping-G30-Irons-Best_252.html d 10.1 by SeannyM. It has some problems (no Bluetooth or FM radio, need to install different apps for the camera and data usage, no off mode charging), but it runs smoothly if you can live with those issues.
Use LagFix from the Play Store to use TRIM on the memory. Use Link2SD and a Class 10 microSD to install all your apps onto a microSD. Leave the 4GB of internal memory for Android and its built in apps. This way, your Ace 2x will run well, store plenty of files and use apps with high memory demands.
This phone is terrible out of the box. Android 4.0.4 is dated, the TouchWiz version of Android is slow, illogical and the single core processr, low RAM and measly 4GB of internal storage will fill up by day one.
This phone is pretty awesome if you know your way around rooting, flashing ROMs, using external storage and using apps such as LagFix and Link2SD. The processor and RAM are low end, you can root it and but SeannyM’s build of CyanogenMod 10.2 runs like a dream. 4GB of storage space is bad, but if you get a Class10 microSD card, you can use that for storage space and Link2SD will let you run apps from the microSD smoothly. LagFix can provide the TRIM protocol that pre 4.3 builds of Android lack, preventing the phone from running slower than it does from initial usage.