The Samsung Galaxy S2 served as the flagship device for the Korean Smartphone giant back in the days of 2011-2012. Surprisingly, it is still quite a formidable device with future-proof hardware. It is one of those devices that were better designed compared to its peers. It supported a mini-SIM and was released in April 2011. It supports both GSM/HSPA technologies, missing the LTE support of newer generation flagships.
The Samsung Galaxy S2 has a Super AMOLED capacitive touchscreen with 16M colors. Having a 480 x 800 pixels display resolution on a screen size of 4.3 inches, the pixel density is quite low at 217 ppi. The device is protected by Corning Gorilla Glass and also supports multi-touch input. It runs on the TouchWiz UI 4.0 platform.
When the device launched, it sported the Android Gingerbread v2.3.4 and was later upgradable to Android Ice Cream Sandwich v4.0.4. It is also further upgradable to Android Jellybean v4.1 with no further official updates. It runs on a Dual-core 1.2 GHz Cortex-A9 CPU working on the Exynos 4210 chipset. It has a Mali-400 GPU.
The device came in the market with two different variants with 16GB and 32GB internal storage capacities. It is further upgradable to 32GB using a microSD card and runs on 1GB RAM. In the camera department, the S2 has an 8 megapixels rear shooter, supporting 3264×2448 pixels and has autofocus, LED flash while supporting Geo-tagging, face/smile detection and touch focus. The rear camera can record full HD 1080p videos at 30 fps. It also includes a further 2MP secondary camera.
Presently, a new CyanogenMod Android 5.0.1 Lollipop CM12 milestone series custom ROM has been released for the Samsung Galaxy S2. According to reports from Team Android, the latest CyanogenMod based Custom ROM is completely based on the AOSP (Android Open Source Project) Lollipop 5.0.1 version. S2 users who wish to update should keep in mind that this is just the experimental Alpha CM12 version; hence, some issues are yet to be fixed.
Keep in mind that when you install this custom ROM, it will surely update and increase the performance of this device and major UI experiences, however, you will lose all warranty with Samsung. The company will no longer be liable to provide further updates to your device, IF ANY. At the same time, you can revert to your original settings and restore your warranty when flashing the device with your stock ROM.
Keep in mind that the new CyanogenMod CM12 range mod is only applicable for the Samsung Galaxy S2. You will not get the desired results by installing in other devices. Always make sure to install Clockwork Mod (CWM) Recovery/ TWRP in order to back up your memory that needs to be cleared while flashing.