What I got out of it was that Tolkien's portrayal was quite good, even in subtle details I hadn't picked up before. Opposed landings are hard, and despite inferior numbers Faramir might have held Osgiliath but for the Nazgul. Denethor lights the beacons (summoning vassals, not Rohan) before troops even leave Minas Morgul; foresight or the palantir at work. Also learn a fair bit about medieval warfare considerations.
Jackson's version... not so good.
(He also looks at how medieval Game of Thrones is: not very. Lots of things are more like the Early Modern period: large armies with regular kit, weak religion (okay, that's more like *late* modern), nationalism.)
See the DW comments at https://mindstalk.dreamwidth.org/527507.html#comments