Did my initial training on the French air force in them in Cognac end of the 1960's, only a few dozen hours on them and very long time ago..
but to answer partially to your questions :
he flying characteristics of the Magister. very simple and nice to fly.
Was it an easy aircraft to fly? Yes relatively. coming from flying gliders ( most of us did in those days ) we knew how to use our feet and keep the ball in the middle.
What were the dangers of flying the type - could you get into trouble easily on the edge of its flight envelope? Not that I recall.
Was the cockpit ergonomically easy to work in ? the front was ok . Full of added bits and pieces over the years as most French cockpits were in those days , not so much place but OK, we did not know any better. In the back definitively not .
How effective was it in the ground attack role? You have to ask the Israelis , they are to my knowledge the only ones that used them in combat . not made for it. It was designed as a trainer .
How effective was it as a trainer? very . except perhaps endurance , 1,5 hour max in cruise ( slow) and 1 h in training with some aerobatic in it .
Always had to look at the gauges all the time when coming back ..
What was its strongest virtue? you could do basically anything with it and get away with it if you were high enough. (You could also smoke in it and get rid of the butt in flight :-) The only military jet you van do this I believe
What was its greatest vice? Underpowered . especially the ones equipped with Marbore I engines, The Marbore II were better but marginally . Ejecting was possible on paper . I do not know anyone that did it though,.But you could put it down in a field and get out of it , landing without gear was no issue ( happened a lot before the Bip-Bips were introduced. , they were repaired and flown back a week later.