I have tried it out with both letting them play the game on there own and with co-op
Just to say my network is 180MB Down and 35MB Up, and my friend who tried with me has 100MB Down and 14MB Up. We noticed no bad sync issues or delays.
He could play my games and i could play his perfectly ( all be it at the lower res/framerate ) the only thing is with this 1 hour play time thing you need to keep resetting it so you they can play ( hope this will be changed in the future however i doubt it ) But you can play the entire game there are no limits to how many times he can share.
Co-op games work great that's all i can say. He may have well been in the same room
The only negative thing i have to say is the 1 hour timer to be honest and i can't comment on minimum network requirements but we had no issues with ours.
another note that i read and thought was cool ( haven't exactly tried ) is that if a friend does not have ps + he can still play your games over remote, he needs ps + to play the co-op version though.
EDIT : I would like to add that i know sometimes something may have all the best spec and be great on paper but just doesn't feel/play right but i can happily say shareplay was a pleasant experience and felt great to use