This is one of the worst Phone ever. Points as below: -Low battery backup 1500mAh -poor image stabilization for primary camera ( so don’t ask for secondary.
Initially Windows Mango OS 7.5 launched with basic issues. such as non expandable memory - Out of available 4 GB internal memory. 2 GB - 2.5 GB taken by apps/OS I think Samsung has already stopped the production. So just cool and relax. if you are windows fan , then go for Nokia Lumia. At last you should buy any other phone in this price range