It's working fine for me. Lumia 1520 on 14393.67 and Dell laptop on 14393.82.
Text comes in and on PC I can reply in the popup. If I miss the popup and go to Notification Center I can get a reply box by clicking or touching the expand toggle (v expand, ^ collapse). Works either way to send a reply.
To start an SMS from PC: use Hey Cortana or type into the Cortana box, "text " and that works for me in all cases.