Sure, it is usable, though the lack of HW acceleration is 'early phase' for me.
Unfortunately, you need to complain to Microsoft that is blacklisting all the current APIs for hardware acceleration.
If Microsoft was less blocking, you would have hardware decoding since a long time.
Isn't it possible to do hardware decoding of certain video streams as of iOS8? Will you be able to do hardware decoding of MKV-wrapped H.264 files in later releases?
For iOS, we have a pretty good patch to do it, yes.
We just have a weird but with M2TS files, but we will merge it during the next month. Expect it for 2.6.0
Hardware decoding is getting finished now, while we still don't have it on iOS.