I can see why some people dislike this: it’s very slow to start, there are differences in set up from the original trilogy, and the whole ‘thing’ is on a very different track from the originals, too.
However, I still thought it was a huge amount of fun! AND I thought it made a nice addition to a fun series – I mean, were the originals really so brilliant that any deviation makes the film terrible? No.
Harrison Ford does look a lot older – 19 years! – but still manages all the physical stuff amazingly well. The film winds forward those 19 years, and we now find ourselves in 1957, facing the Cold War rather than Nazis. Well, it wouldn’t be feasible to pretend time hadn’t passed, really! Unfortunately, it does mean there’s a bit more ‘set up’ and explanation rather than just throwing you into the story. And a very long build up, imo.
Once it gets going, though, it’s just as much of an adventure as before, just… in a slightly different direction. And really, you cannot complain about plausability here compared to the Ark of the Covenant and Holy Grail – these things are just as much myth as anything presented here, people!
So, go with an open mind, kick back, and just enjoy what there is. The 1980s have gone; the film does well to fit as well with the rest of the series as it does.