There seems to be an almost universal opinion in instructor circles, that home built simulators are bad.
Unsupervised use of any sim will of course reinforce and embed any small mistakes because you get away with them.
Just like the millions of pounds worth of full motion airliner sim, you will get more out of it if someone is watching you and checking your actions against a list. I was lucky enough to be able to persuade my wife to assist by watching and listening for various actions.
The staring at instruments is an old fashioned issue, easily avoided by use of photo realistic scenery and no instrument panel. Just "fly" the machine based on what you can see out of the window.
A simple key press will show/hide the panel and allow the student to plod along without the distraction of instruments and gauges.
I wonder how many of the instructors who are against the use of sims, have experience of the latest thing available to students.