Stockfish official code is written in C++. If you rewrite it using C, you simply get closer to the processor level for extra speed but you sacrifice portability of the code among systems and you face more difficulty in translating the existing. It's kind of a downgrade for a programmer but if it makes your engine run faster, why not?
C++ is much more ergonomic and modern by definition but chess programmers always prefer speed. So CFish is a good idea.
After the release of Stockfish 8, CFish followed the official branch and thanks to Aprijal, we have an Android port of CFish. I can speak about 20% more kNps on my MTK6752 processor compared to SF8. It's by far the fastest Stockfish i've ever had!
GET CFish 8 AP for all builds
Previous versions i forgot to share last month (oops!):
GET CFish 20161017.AP for 32-bit arm7 pie
GET CFish 20161017.AP for 64-bit arm8