For under a 1,000$ with a kit lens, it's currently the cheapest full frame camera that you can buy today!
Does it lack performance and image quality compared to a more high-end full frame or APS-C cameras? Not at all, infact it has higher scores on DXO mark than the D500 - the top of the line crop sensor camera from Nikon which costs 1,800$ for vody only, and the D4 the top of the line full frame sensor camera which costs 3,500$ for body only! Still you can't make a comparasion for shooting sports because the Nikon are machine gun beasts, but for the average Joe, the Sony A7 is more than capable.
So what's the catch, why is it so cheap? First of all it's 4 years old. It's successors the A7II, the A7III and now the A9, are more capable and have more features, so the older camera models get massive discounts.
Bottom line is - you don't have to buy the latest and most expensive camera that your salesman will pitch to you. Don't be scared to buy a 5 year old camera. For example, my D7000 was introduced in 2010 and I could keep it 10 more years and take great photos with it.
In the following days I hope to get out more often and compile a nice photo gallery from the A7.
Bonus, there are adapters available for literally every lens mount you can imagine, so I'm very excited to try some old lenses on this camera.