Shin Ultraman was so fucking good, y'all
I'd say it's been a while since I've enjoyed a movie so unabashedly being what its loves and wants to be, but I did watch Glass Onion like two months ago.
That said, even though I'm rather light on my Ultraman knowledge (only some hours spent on the original, R/B, Z and Orb) I was able to follow some of the specific lore stuff well. I'd still say it's a bit hard to jump in blind, but if you're in it just for a humanoid alien shooting stuff, you'll get some of that at least (along with the Shin series' patented beaurocrat chattin'!)
I don't know why Shin Godzilla's didn't hit me as hard (it's just as good), but oh my fucking god the soundtrack here is on point for every single second it plays. Just so incredible on both listening to individual pieces but also just setting the backdrop and tone for their scenes. Desperately hoping a vinyl release happens, which I don't doubt it eventually.
In any case, go see this movie so I don't have to wait another 8-10 months to maybe see Shin Kamen Rider in a theater here.