Within 2 months of mild use and charging with the original Sony charger, it swelled so much that it wouldn't fit in the camera.
During its use, it never dropped below 20% and it was always stored outside the camera. I would not buy again!

They're just fine, I've bought these before.. good value-for-money ratio. My previous ones lasted about 2-3 years of use before their power dropped (roughly: 20 minutes of 4K recording - while at first it was 40+ minutes) and of course recently they started to swell a bit --you notice it when it gets a bit hard to remove the battery from the camera body-- so it was time for retirement. Cheers!

I bought a Fujicell NP-FW50 battery for Sony (via Skroutz) from Galaiosphoto. Obviously, it had been on the shelf for a few years as it doesn't hold a charge in the camera. In a few days, it dropped to 10% without serious use (just a format & about 10 photos). When I received it, it didn't show any charge on my external NP-FW50 charger and it made me suspicious. I charged it inside the camera and it seemed to work. Also, the fact that it was completely empty when it arrived was another sign, as lithium batteries always come with a charge of up to 50% from the factory.

A great battery! I had bought it as an extra when I purchased my camera in 2013, but it was expected to die out over the years. I highly recommend it.

Good battery for a second if you use it for a photo. Generally, for videos, I had bought two but now they don't last more than 30 minutes of video. If you pay a LOT of attention to their charging and don't let them run out in the camera, maybe they will last.
If you want a battery just for backup, then take it as a cheap solution. If you want to use it as a second battery, then spend money and get the Sony one. It will last much longer!