I have no problem with all of the concepts around the "new" espionage. I have a major problem (and always have with Civ) with the computer cheating. It is way too easy to steal technology, you never get more than a handful of spies, when in late game you could have dozens of cities they can steal from, and if you are the technology leader you can't steal back. So your only real recourse is war, which will destroy you diplomatically because of the insane warmonger penalty that never goes away!
They should at least give the option to build spies again so we have a legitimate chance of stopping every civ from stealing technology with ease.