Hi everyone, I Own vivo Y51L and infact I am writing this review from same phone. I am using vivo Y51L from last 8 months and I can say its working quite well.
1) Battery backup is excellent as I am using two sims and one is 4G network other is 3G and I can assure you , battery backup is very nice .
2) Display quality of this phone is also quite good.
3) Camera : front is 5 mp which gives clear images, back camera is 8 mp which is clear and good but I can say its video quality is very nice.
4) Sound quality is fine you need good earphones though.
5) 2 GB ram is enough for regular app.
So Vivo Y51L as per my usage and experience , which is moderate usage is excellent phone in this price range. And I must say from last 8 months this phone has not hanged at all, not even once.