I am a long time Saga player and LOVE it.
Damn it, I'm going to stick my neck out here, and say it's my favourite wargame of all time.
There, I said it. I can't take it back.
But.
I'm not sure I see the value in evaluating it in terms of a historical game, because it's not.
Truth is, it doesn't represent any period 'well'. I think to ask that question of it is asking the wrong question. Like asking if a tomato makes a good football - it can be used as that, but that misses its real purpose.
Saga is a fantasy version of the periods it covers. It bears little resemblance to history. It is not a simulation, it is very firmly in the 'game' camp, which it does extremely well.
And I love it for that.