I'm using MR UNO plan, connectivity wise is same as Starhub as it uses Starhub network. Calls sometimes don't get in, internet speed latency is high (lower the better), hence loading websites will be slower. Reception wise, I feel still average. If you exceed the allocated data bundle, the throttled speed will be painfully slow.
I'm using M1 as main & MR UNO as secondary line. Set to use M1 for 1st 3-weeks of the month & MR for 4th week as the last mile. So far MR line working fine on my OP6T, nothing unusual happened.
But my mum complained about the connection on her Nokia 3310, so not sure it's due to phone quality.