General thoughts from someone who hasn't seen "Let It Be" (and probably won't for a very long time now):
The infighting is mostly relegated to one bit where George gets mad that Paul keeps telling him what to play, immediately after which George LEAVES THE BEATLES! Apparently, there was a cut tense interaction just before this between George and John that led to the walkout (idk if that's in "Let It Be" or not), which would certainly make George leaving make more sense. As it is, it's pretty confusing.
There are a few mild arguments, but watching this you're more likely to think, "man, these guys LOVED each other!" There's tons of goofing around, hugging each other and general merriment. I'm guessing the real story is somewhere in between what's portrayed in the two movies? There *was* 60 hours of footage recorded in total.
Paul totally seems to be in charge at this point, contributing the most songs, and generally seeming to be the most talented. John mostly just goes with the flow, while Yoko sits next to him LITERALLY THE ENTIRE TIME (!)
Imagine having a band and trying to be in a creative circle and get things working, and the rhythm guitarist's wife is just sitting there? Hella weird. Linda shows up at times to take photos and stuff, but she's not sitting next to Paul when he's playing. Yoko does do her screaming/yelping bit when they jam a couple times, which they seem to have fun with. lol@Paul generating feedback like a true rocker. Young Heather McCartney does a pretty funny impression of the yelping later on.
after much dicking around, once Billy Preston turns up, the band gets like a million times better almost immediately
"Get Back" started as a funny protest song
Ringo and George writing "Octopus's Garden" together
the early versions of songs from solo Beatles' albums
Paul noodling around until he comes up with "Let It Be" in the background while people are walking around talking and not paying attention
also it's just fun thinking to yourself what the correct lyrics should be, as they struggle to come up with them, "no, the California grass part should go there!")
Glyn Johns and his amazing psych wardrobe
Mal Evans' moment in the sun during "Maxwell's Silver Hammer"
all of the "Abbey Road" song bits are great
*some* of the goofy voices and jamming and alternate lyrics are great fun, but dear god is there a lot of it
I guess my main problem with the movie is out of the "Let It Be" songs I only really like "Get Back" and "Two Of Us," and think a few others are okay, which means a hundred million tries at "Don't Let Me Down" and "I've Got a Feeling" don't really do much for me. (also, did John mess up the lyrics on purpose on the roof or did he STILL NOT KNOW how "Don't Let me Down" goes after all that time?)
I'd say it's definitely worth a single watch, particularly if you're interested in seeing good songwriters write songs, but if you're not a Beatles fan I can't imagine being entertained by this. Part two in particular is really ####ing boring.