Is this a stand-alone film...

Watching at least the original (if not the entire trilogy) kind of is, if you want to have any idea what they're fighting for in Matrix 4. I think at the end of the day, while it does rehash some of the original 3 movies, it does venture further into the Matrix universe... Complete with returning characters... But to get a sense of where they're going, it definitely helps to see where they've been; and not just the vague, incomplete clips of the original trilogy that were displayed as flashbacks or footage.

You definitely have to watch the first three.

This one... not so much :-)

Seriously, this is a sequel. There are direct references to events these same characters been through together. However, it kind of tarnishes the originals by inventing a far fetched, ridiculous scenario in order to introduce a new status quo. Which is not really new... and not good... and all other aspects of this movie are vastly inferior to the originals.

The drop in quality in lighting, cinematography, fight coreography, dialogue, message, etc. etc. is astiounding.

So this is why you shouldn't define "The Matrix" in your mind by watching this film first. This atrocity cannot be your first impression about the Matrix universe. Please watch 1-3 first!