The best way I could think to describe it for people to judge is this - if you are the sort of person who loved the entire HBO Chernobyl series (accident, cover-up and court-room style investigation afterwards) and wanted to see something similar but concentrated heavily around a single main lead in a condensed time-frame of 3hrs then you'd probably like this almost docu-drama too. I also can see why people are saying that the "need" to see this in IMAX is overblown as I can't imagine any scene I saw in my normal Vue cinema being made so substantially different by IMAX that it would've changed my view on that scene.
Personally I absolutely loved it and it was an easy 8/10 for me. I would split the film into two sections, the build-up to Trinity and then the aftermath. I think most people would be interested by the "build-up to Trinity" section, but for me I was absolutely riveted by the other section which is what others are describing (accurately to them) as "Men talking in a room" aection, which might seem boring to others but to me each scene was one in a series of acting masterclasses, with every little facial tick, expression, eye contact between speakers, body language etc holding far more importance than what the words being said meant.
If all that kind of stuff blows past folks (no criticism here) then its completely understandable why they'd get bored in the second section just watching numerous scenes of people talking. However, one thing I found annoying, and its becoming a common criticism of Nolan's recent directional style, is that it felt like he's trying to add extra complexity into a story as his own cerebral exercise, at the expense of everyday Mr & Mrs General Public. I know it would have made for a less brain-twisting film, but if he'd just kept a linear timeline with just the occasional short flash-back then the film would've been far more palatable to the average cinema-goer and would probably have done even better at the box-office that it currently has and got better reviews.
Someone else mentioned the "Men in rooms " section was a bit like The West Wing (which I also adore) and whilst I can kind of see that point around the acting, a Sorkin script runs absolute rings anything Nolan has created, which is another one of the recent criticisms of his films - technically detailed Genius but lacking genuine human warmth/appeal in the writing (someone described it as how an advanced AI would write, able to technically describe emotions but having no real understanding of them).
I'll definitely be getting a hard copy once its for sale as it's been the best film I've seen this year, but I can also see the very valid criticisms people have had with it and I worry that Nolan is becoming like a pop band who make their music more and more complex with each album in a bid only to impress other musicians but at the cost of losing the the fans who still just like pop music.