Just going on the pics then it looks reasonably ok to me. Without DIY building then 3.5K don't buy much machine at this size.
Obviously can't see the condition of the ballscrews and mechanics etc but from the outside condition it looks ok and is the typical 3 axis centre driven gantry style machine that doesn't look like it's had a hard life.
The electrics are nothing special and can easily be sourced and replaced if troubles arise.
The 4th axis looks ok and is a duel purpose affair that can be used has a trunion style table like shown in the pics or the flat plate can be removed allowing it to be used like a lathe with an adjustable length tail stock.

Can't much more than that really without seeing it.

It's like this.? . . . Unless your prepared to DIY build then you won't buy cheaper.