Vivo Y55s in not a very good phone on its high prize.The vivo Y55s features are:
Display size: Vivo Y55s has 5.2 inch display but many brands give atleast 5.5 inch display at same prize.
Battery: Vivo Y55s has 2730mah whis is not good for the users.Not only the battery life is bad but also the battery is non removable.
Ram and Processor: Vivo Y55s has 3gb ram but it has 1.4Ghz quad core processor which is unsatisfyed on its prize.For quad core processor the phone hangs many times.
Android: Vivo Y55s runs on android marshmellow( 6.0) .It can update to android nougat( 7.0)
Camera: Vivo Y55s camera quality is very good.It has 13MP front camera for good selfie and 5MP back camera.
Network: Vivo Y55s supported 4G network and both sim slots are 4G LTE.Vivo Y55s is also a VOLTE set.