Picture quality is very good, though i did some fine tuning manually from advanced settings rather than sticking with the preset modes. Sound is average, better if you connect to external speakers, i tried with aux connection but it had a lot of static. My home theatre doesn't have an optical port so I've ordered an optical to analog 5.1 channel converter so I'll check with that once it arrives. But overall it's definitely worth the money.
I was in two minds between Mi 4A Pro and this one, but I believe Onida build quality is better than Mi and I didn't want the Android bloatware that Google bundles with stock android devices and I liked the simple fluid interface of fire tv so went for this.
I don't have much experience with VU smart TVs, but I've been using a VU non smart TV since two years in my other room and it has A+ grade panel and even though it is HD ready, the picture quality is as good as full HD and the sound is decent as well.