I sat through to the end and my conclusion: ultimately expensive rubbish.
I liked the first couple of episodes - interesting characters set up, mysterious computing facilities spies, murder. But after episode 4 it all fell apart into lots of actors doing blank staring or ‘tearing up’ : signal they are having deep thoughts! ( or no decent lines).
People’s behaviour - we are told - all goes ahead on pre-determined tram-lines. Maybe that’s why the writers didn’t feel the need to bother helping us viewers understand why anyone acted as they did - apart from Forrest who is driven to have people killed because he feels guilty about the death of his daughter. But like most psychopaths - he doesn’t feel guilty about anything else he does - shifts that blame for the outcomes of his actions onto the people he does it to. But most fiction that has psychopaths at its centre doesn’t have them achieving their objectives at the end and living in a universe that’s designed around their wish fulfilment. Not sure if we were meant to think it was all OK in the end because all those dead people are now ‘alive’ as programs in a his ( Forrest’s) simulation.
He certainly believes it is - that the ‘sim’ boyfriend he’s now given Lily is a great replacement for the two ‘material’ boyfriends he caused to be killed.
The metaphysical science stuff was either poorly explained or contradictory. As others have pointed out it confuses ‘cause’ and ‘reason’ as it expounds its theory of predetermination. It leads us to believe that a highly intelligent person will risk falling off a dam and dying because if he dies in this universe he’ll simply wake up in another - in which he didn’t die! Is this the the Christian version of multiverse theory? Whenever you die you move on to heaven or hell as you’re simply bumped into the next universe!
And Lily our heroine - the only person in the world to operate free will outside this predermined universe - wanders around a great deal of the series wordlessly in a state of shock in her underpants and bare feet. Forrest describes her as ‘brave’ and ‘different’. To the audience she seems passive, and prone to taking the worse options amongst all those open to her. In our house everyone spent the last half hour of the last episode yelling at her: just shoot him NOW! Of course being Lily she just stared wordlessly at us as a tear ran down her cheek.