My first takeaways thoughts are these:
Watching again - and really paying close attention

Next... I am stunned, frankly, at some of the revelations of the original script, versus the American dubbed scripts that I'd basically memorized through repeated viewings as a child (and growing up). Ito (sorry, "Ide") openly guesses that Ultraman & Hayata are one and the same!? It's much, much more ambiguous in the American version, (which I truthfully prefer for this aspect). Interesting. But for me the most stunning example of the changes in the adapted scripts, up to this point, is the totally different ending or tone of episode #15, "The Terrifying Cosmic Rays". The original ending is much, much darker. It goes from being loosely wrapped up in the American version to being, possibly, the start of something far more sinister; with the children being painted as indifferent to the destruction and suffering caused by monsters and more interested at the prospect of creating their very own living monsters - potentially horrific consequences be damned! Wow.
And I still don't quite get episode #17, "Brother from Another Planet". The script is really a mess and just does some really stupid things and is so inconsistent with the narrative compared to the rest of the series. The whole "Hoshino brings Hayata his Beta Capsule for no real reason, apparently(?) doesn't know what it's for, nor figures out the secret identity, etc." is really a headscratcher. I realize that there are a lot of "?/WTF" moments in this and many other toku shows, but this one's always been one of my least favorite UM shows because it just does so many one-time, dumb things and creates big questions that are never answered. (Of course I have 25 episodes to go, so perhaps I'll find more 'hidden secrets' and/or answers as I roll along.)
Same 'WTF' thing goes for the end of episode #16, "Science Patrol into Space". Hayata apparently changes into Ultrman with Captain Muramatsu right there in the Jet VTOL with him, yet he doesn't tell Arashi about it and never acknowledges it again. Plus we see Hayata existing physically separately from Ultraman at the same time ??? I thought he literally 'became' Ultraman? Does he just go into a coma... or does he disappear and is replaced by Ultraman... or are they one & the same. Again, some weirdness that stands apart from the other entries in the series. (And I am guessing that episode #16 was broadcast out of order originally, as Hoshino is shown dressed in his SSSP uniform at the end of the episode but doesn't become an official member until episode 18.)
THOUGHTS, GANG???