[ReadyCodyOne]

Finally getting myself a new phone. Is an S5 beefy enough (maybe with a 128GB SD card) for being used as a Kodi box? It has MHL so I can hook it up to my TV directly with a USB - HDMI  MHL cable.

Is there anything else I should consider about this?

[Klojum]

If it has been upgraded to Android 5.x/6.x, then it should be possible. The 128GB card's size is not the biggest challenge, but its read/write speeds can be a user-experience factor.