I ordered my first Sky Sports Day Pass today to watch PL & NFL games on a new Samsung 6-series SMART TV and am having an equally terrible experience. The streaming quality is super frustrating ranging intermittently from 30% -90% optimal resolution with the deterioration occurring randomly throughout the day. Hardly value for money. I've sent a complaint to NOW.tv and would be interested to see what the response would be to that and to this thread.
I'm on a humble 3 meg adsl connection; fortunately the app shows the stream speed when you start watching.
(You'll also see it again if you press the PLAY button, whilst watching.)
You don't see it if using one of the NOWTV black boxes.
But I too see varing quality; my best is usually around 2017, but can drop, whilst watching a show to the low hundreds; usually recovers fortunately.
I wonder if some popular shows could suffer from contention at NOWTV end?