The A7Sii was quite seminal being the first FF 4K mirrorless with IBIS that could literally see in the dark. Noise was never an issue with that camera since it had such great low-light performance across the ISO field. The real problem with these earlier A7 cams was the horrible AWB in mixed lighting combined with so-so CS. Andrew had a classic hilarious YT video about the A7Sii zombie skin tones. Sure you could somewhat correct it in Davinci but 8-bit really isn't the best for heavy color correction not to mention the waste of time. Daylight shooting not so much an issue but the camera had a few other cons brought up in that video such as slow AF, harsh highlight roll-off, poor battery life, build quality issues etc.
Still for the current used price its a great little budget camera if you find one in not too battered state (they honestly haven't held up well) and don't shoot much mixed lighting.
The A7iii fixes most of the A7Sii issues both in build, battery life but also AWB/CS. Also uses oversampled 4K for more detailed current IQ. But they still go for +$1.5K used. Not bad but not phenomenal considering you can now get a 10-bit cam for not a lot more from other manufacturers..