Hi there..
I will say it depends on where you want to travel. Are you staying mainly in Manhattan?
What I found was, there are a few main routes that travel North-South (like the N,R approx. along Broadway) and then there are a few main stations which are good for transferring (like 14th, 34th etc) so I just stuck to those & walked a few blocks when I emerged. So no, not complicated. Yes, the staff were great! Loud & enthusiastic (be polite to them!) and I much preferred the subway to taking a cab, due to traffic & the fact that I couldnt tell if we were going the shortest route.
Ok, probably not like a native new yorker uses the subway, but if you are staying mostly in Manhattan you'll be fine (I'm going back next year & cannot wait!)