Yes, I paid for the PLAYz app and use it almost daily. For me it is money well spend.
Subtitles work without problems. If subtitles are available you can turn them on or off, or select which subtitle you want if there is more than one.
I found that changing or selecting subtitle does not work very well from the screen right before you play something. It works best, and without any problems, while playing something by opening the subtitle menu while your movie is playing, so not by going back, but while playing press OK, go to the right and select the speech balloon icon on bottom right of your screen.