These are not bad.
I like the mechanical stuff and a lot of the sculpting is good. I like the way cast pieces are used to keep things uniform where they need to be but there are two areas that still need work; faces and attention to detail.
The faces look amateur and mostly like masks.
The hands on some have fingers of different widths that look wrong and there are places where the sculptor seems to have got bored and not finished.
I'm an amateur sculptor too and I struggle with faces sometimes but it's a case of get some practice in and have reference pix with you.
These are a good start but need a little more polish.